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NAM2011 - All Poster Summaries

This is a complete listing of all 129 entries

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Resonances in 19Ne with relevance to the astrophysically important 18F(p,α)15O reaction.

Author: David Mountford

University of Edinburgh

Co-Authors:

Session: APP: Astroparticle Physics

Presentation type: Poster

Summary:

The decay of 18F via β+ decay is the main source of gamma ray emission from novae. The main nuclear uncertainty in this process comes from the 18F(p,α) reaction, which proceeds through resonances in the compound nucleus, 19Ne. In 2006 Dufour and Descouvement[1] proposed, through microscopic techniques, the existence of two previously unseen energy levels in the 19Ne nucleus, at ~6 and 7.9 MeV. In light of this there have been two published attempts in the search for the higher of these states. While Dalouzy et al.[2] claim to have discovered the elusive state, Murphy et al.[3] find no such candidate. The aim of this work is to address this contradiction and come to a firm conclusion as to the possible existence of this new state. An experiment has taken place that uses a 4MeV/u 18F beam, degraded to ~1.9MeV/u, incident upon a thick CH2 target. The data is currently being analysed within the R-matrix formulism and preliminary results are presented here. [1] M. Dufour and P. Descouvement, Nucl. Phys. A785, 381 (2007) [2] J.C. Dalouzy et. al., Phys. Rev. Lett., 102, 162503 (2009) [3] A.S. Murphy et. al., Phys. Rev. C79, 058801 (2009)

A Multiwavelength View of Star Formation Across Cosmic Time

Author: Alyssa Drake

Astrophysics Research Institute, LJMU

Co-Authors: C.A.Collins (LJMU); P.A.James (LJMU); C.J.Simpson (LJMU); I.K.Baldry (LJMU);

Session: COS: Cosmology and large scale structure

Presentation type: Poster

Summary:

Understanding the formation and evolution of galaxies relies heavily on the accurate determination of how when and where stars were formed. Tracing the evolution of the cosmic Star Formation Rate (SFR) is an essential tool for constraining galaxy formation and evolution models. The generally accepted view of hierarchical galaxy formation has been challenged in recent years by observations of “downsizing” in galaxies: star formation occurring earlier in more massive systems. Although this behaviour was first deemed to be anti-hierarchical, it has since been proved to be a natural part of the bottom up clustering process of Dark Matter (DM) halos. We aim to investigate the evolution of SFR as a function of environment and stellar mass using several narrow band filters. This way we can study a number of redshift slices spanning 10 Gyr, and start to place constraints on downsizing. The second half of the project will take several square degrees of data form VISTA to focus on examining the processes and mechanisms that trigger and halt star formation, and their evolution with cosmic time.

CBASS: a C-Band All Sky Survey

Author: Melis Irfan

JBCA, University of Manchster

Co-Authors: CBASS collaboration

Session: COS: Cosmology and large scale structure

Presentation type: Poster

Summary:

C-BASS, the C-Band All Sky Survey, is in its first phase of data capture. This 5GHz survey of sky intensity and polarisation will be a vital tool in the removal of polarised foregrounds from CMB data. C-BASS consists of a northern hemisphere telescope, situated at the Owens Valley Radio Observatory (OVRO) and a southern telescope in South Africa. Both C-BASS telescopes will produce moderate resolution (45' HPBW) maps, in both intensity and polarisation, of the Galactic synchrotron emission at 5 GHz. Not only will the maps provide polarised foreground measurements for component separation techniques; they shall also probe into the physics of the Galactic interstellar medium. At present, observations of the Northern sky are under way at OVRO, as well as development of techniques and software for astronomical calibration, atmospheric correction, and interactive data quality control and analysis. The first maps of the Northern sky are forthcoming. We will give an overview of the telescope set-up, its calibration and a display of its mapping capability. This will set the scene for the upcoming release of the northern C-BASS maps as well as the completion of the South African C-BASS telescope.

Improving Dark Energy Figures of Merit in Future Galaxy Redshift Surveys

Author: Edward Macaulay

University of Oxford

Co-Authors:

Session: COS: Cosmology and large scale structure

Presentation type: Poster

Summary:

Galaxy redshift surveys have already placed strong constraints on alternatives to dark energy, in particular with the detection of baryon acoustic oscillations, and the measurement of the growth rate of cosmic structure. Forthcoming generations of surveys should improve these constraints further, and extend the measurements to higher redshifts. I will present results of Fisher matrix forecasts for such surveys, focusing on the effect of practical survey design considerations on dark energy figures of merit. I will include results on the effect of contamination due to redshift errors, and the choice of target redshift distributions to optimize cosmological constraints.

Vorticity in the Early Universe

Author: Adam Christopherson

Queen Mary, University of London

Co-Authors:

Session: COS: Cosmology and large scale structure

Presentation type: Poster

Summary:

Vorticity is ubiquitous in nature however, to date, studies of vorticity in cosmology and in the early universe have been quite rare. In this work we use the technique of cosmological perturbation theory to investigate vorticity in the early universe. At first, or linear order, we reproduce the standard result that vorticity decays with the expansion of the universe. However, the higher order theory exhibits a qualitative difference from the linear order theory, namely that different types of perturbation (classified as scalar, vector or tensor) do not decouple. We show that at second order vorticity is sourced by a term quadratic in linear order energy density and entropy perturbations. This is a generalisation of previous work which focused on barotropic fluids, and is an extension of Crocco's theorem from classical fluid dynamics to a cosmological setting.

2-D Time-frequency analysis of phase coherence of solar wind turbulence

Author: Olivier Fauvarque

Ecole Normale Superior, Imperial College London

Co-Authors: F. Sahraoui (LPP/CNRS-Ecole Polytechnique-UPMC)

Session: DAT: Solar and space data processing

Presentation type: Poster

Summary:

Several observations in space plasmas have reported the presence of coherent structures at different plasma scales. Structure formation is believed to be a direct consequence of nonlinear interactions between plasma modes that depend strongly on the phase synchronization of those modes. Analysing directly Fourier phases is however very tricky due to their dependence on an arbitrary time origin and to their 2Ï€ periodicity (which makes the phases appear completely mixed/random, even when they are not!). A method, based on Surrogate data, has been developed recently to solve this problem and to allow one to systematically detect coherent structures in turbulent signals [Sahraoui, PRE, 2008]. This 1-D method, however, suffers the weakness that is it can estimate the scale of the structures but only over the whole used time series. Here we present a new version of the method that makes a 2-D analysis of the time series, i.e., in the time and the scale (frequency) domains. This makes possible to estimate the size of the structures and to localize them in time. After validating the new method on synthetic data, we will show applications to the Cluster data. In particular, we will present recent results on coherent structures at small/electron scales in the solar wind. A discussion of the consequence of such observations on theoretical modeling of solar wind turbulence (e.g., weak versus strong, intermittency) will be discussed.

Feature detection algorithms in HELIO

Author: David Perez-Suarez

Trinity College Dublin

Co-Authors: P. Higgins (TCD); L.D. Krista (TCD); P.T. Gallagher (TCD); N. Fuller (Paris Observatory[obspm]); X. Bonnin (OBSPM); J. Aboudarham (OBSPM); C. Renié (OBSPM); G. Pierantoni (TCD)

Session: DAT: Solar and space data processing

Presentation type: Poster

Summary:

The HELiophysics Integrated Observatory (HELIO; www.helio-vo.eu) is an advanced software system, funded under FP7 e-Infrastructures, that provides a set of data search and retrieval services to study the heliosphere. One of primary services is the HELIO Feature Catalogue (HFC) which provides access to a complete catalogue of automatically detected features in the heliosphere. The detection algorithms will not only be used to populate the HFC, but will form part of the service allowing users to run jobs on different data or with different parameters on the grid computing facilities provided by Grid-Ireland (www.grid.ie). Here, we describe the detection algorithms of the first features implemented on the HFC (Filaments, Active Regions, Coronal Holes and Sunspots) and how they are being used within HELIO.

Isolating CME signal in coronagraph images

Author: Huw Morgan

Institute for Astronomy, University of Hawaii

Co-Authors: J. Byrne (Institute for Astronomy, University of Hawaii)

Session: DAT: Solar and space data processing

Presentation type: Poster

Summary:

A deconvolution method is used to separate LASCO C2/C3 images into dynamic and quiescent components. The large set of dynamic images collected over 14 year contain all observed CMEs of all sizes. We describe how this wealth of information can be further reduced and the possibilities for statistical analysis. In particular, wavelet edge detection techniques enable the structural categorization of CMEs.

On the Multi-spacecraft Determination of Periodic Surface Wave Phase Speeds and Wavelengths

Author: Claire Foullon

University of Warwick

Co-Authors: C.J. Farrugia (UNH, USA), A.N. Fazakerley (MSSL/UCL, UK), C.J. Owen (MSSL/UCL, UK), F.T. Gratton (CONICET/UBA, Argentina), R.B. Torbert (UNH, USA)

Session: DAT: Solar and space data processing

Presentation type: Poster

Summary:

Observations of surface waves on the magnetopause indicate a wide range of phase velocities and wavelengths. Their multi-spacecraft analysis allows a more precise determination of wave characteristics than ever before and reveal that approximations, which take a predetermined fraction of the magnetosheath speed or the average flow velocity in the boundary layer, can overestimate phase speeds. We show that time-lags between two or more spacecraft can give a qualitative upper estimate, and we confirm the unreliability of flow approximations often used by analysis of a few cases. Using two-point distant magnetic field observations and spectral analysis of the tailward magnetic field component, we propose an alternative method to estimate the wavelength and phase speed at a single spacecraft from a statistical fit at the other site.

Study of Anisotropic Turbulence using the Undecimated Discrete Wavelet Transform

Author: Khurom Kiyani

Imperial College London

Co-Authors: O. Fauvarque (Ecole Normale Superior, France; Imperial College London, UK); S. C. Chapman (University of Warwick, UK)

Session: DAT: Solar and space data processing

Presentation type: Poster

Summary:

In-situ spacecraft measurements of the solar wind at 1AU show a highly turbulent plasma with a spatio-temporal structure consisting of a large continuous range of scales. This multi-scale nature is exhibited by a broad-band power spectral density spanning several decades from scales of the order of solar structures to the electron Larmor radius. The nature of the magnetic fluctuations in such a medium is highly anisotropic; with fluctuations being ordered parallel and transverse to the 'background' magnetic field. However, with no clear separation of scales the traditional distinction between a background field and the fluctuations is no longer apparent. In this poster we show that the Undecimated Discrete Wavelet Transform (UDWT) is not only a natural way of defining a local scale-dependent background field and fluctuations self-consistently; it also possesses additional benefits such as the retention of event information, spectral completeness and importantly fast computation amongst other things. We will illustrate the use of the UDWT by presenting some key statistics in the analysis of anisotropic turbulence, as applied to high-cadence magnetic field measurements from the Cluster spacecraft.

The Hilbert-Huang transform: a new approach for studying quasi-periodic pulsations in solar flares

Author: Jennifer (Harris) Hershaw

University of Warwick

Co-Authors: A.R.Inglis (NASA Goddard Space Flight Center); V.M.Nakariakov (University of Warwick, Pulkovo Observatory)

Session: DAT: Solar and space data processing

Presentation type: Poster

Summary:

Flaring energy releases are rapidly evolving and generally short-lived processes, often exhibiting anharmonic oscillations, and this should be taken into account in their analysis. We test the applicability of the Hilbert-Huang transform method, which was specifically designed to work for nonstationary and nonlinear data, to the analysis of oscillatory flaring light curves. Both synthetic and natural datasets are analysed using empirical mode decomposition with the Hilbert transform, and the results are compared against Morlet wavelet analysis.

Turbulent characteristics of the intensity fluctuations in the Hinode/SOT images of a solar QP

Author: ERSILIA LEONARDIS

UNIVERSITY OF WARWICK

Co-Authors: S.C. Chapman (University of Warwick); C. Foullon (University of Warwick)

Session: DAT: Solar and space data processing

Presentation type: Poster

Summary:

The Solar Optical Telescope (SOT) on board the Hinode spacecraft provides long time intervals of observation of the solar corona via images at simultaneous high spatial and temporal resolution. We focus on specific Calcium II H-line observations of a solar Quiescent Prominence (QP) which exhibits several small scale up-flows with very highly variable dynamics suggestive of turbulence. Fluctuations of bulk quantities associated with a turbulent field show similarity in their non-Gaussian statistics leading to the following scaling for the pth moment of the structure functions: Sp(δ)=<|f(x+δ)−f(x)|^p>∼ δ^ζ(p), where δ is an observational scale and ζ(p) are the scaling exponents. Recently, a generalization of this scaling has been found for turbulent systems of finite size - i.e. in the quiet solar wind - which instead exhibit a single robust scaling function g(δ/δ0) such that Sp(δ)∼Sp(δ0)g(δ/δ0)^ζ(p), where δ0 is some characteristic parameter of the flow. We test this generalized scaling by performing statistical analyses such as Generalized Structure Function (GSF) and Extended-Self Similarity (ESS) on the intensity fluctuations of the prominence. We verify the non-Gaussian nature of the spatial fluctuations and, consistently with a turbulent flow of finite size, we find evidence of ESS along the directions either longitudinal and transverse to the bulk (driving) flow.

Web-Based Data Processing System for Automated Detection of Oscillations

Author: Valery Nakariakov

University of Warwick

Co-Authors: R. Sych (NAOC, Beijing, China and ISTP, Irkutsk, Russia), S.A. Anfinogentov (ISTP, Irkutsk, Russia)

Session: DAT: Solar and space data processing

Presentation type: Poster

Summary:

A web-based, interactive system for the remote processing of imaging data sets (i.e., EUV, X-ray, and microwave) and the automated interactive detection of wave and oscillatory phenomena in the solar atmosphere is presented. The system targets localised, but spatially resolved, phenomena such as kink, sausage, and longitudinal propagating and standing waves. The system implements the methods of Periodmapping for pre-analysis, and Pixelised Wavelet Filtering for detailed analysis of the imaging data cubes. The system is implemented on the dedicated data-processing server http://pwf.iszf.irk.ru, which is situated at the Institute of Solar-Terrestrial Physics, Irkutsk, Russia. Input data in the .sav, .fits, or .txt formats can be submitted via the local and/or global network (the Internet). The output data can be in the png, jpeg, and binary formats, on the user’s request. The output data are periodmaps; narrowband amplitude, power, phase and correlation maps of the wave’s sources at significant harmonics and in the chosen spectral intervals, and mpeg movies of their evolution. The system's performance is illustrated by its application to the analysis of 3-min oscillations above sunspots, observed with SDO/AIA and NoRH.

A Fermi-LAT Study of the Active Galaxy NGC 1275

Author: Kate L Dutson

University of Leicester

Co-Authors: R.J. White (University of Leicester) J.A. Hinton (University of Leicester) A.C. Edge (Durham University)

Session: EXP: Explosive transients, AGNs and black holes

Presentation type: Poster

Summary:

The active galaxy NGC 1275 has now been detected in High Energy and Very High Energy gamma-rays (using the Fermi-LAT and MAGIC telescopes respectively), raising questions about the mechanisms responsible for producing such energetic emission in the centre of the well-known Perseus cluster of galaxies. Could it be associated with the relativistic outflow from the central engine, which is believed to inflate bubbles tens of kiloparsecs into the Intracluster Medium, or do the gamma-rays originate from larger scale structures? The temporal variability of the Fermi source, and spectral evolution over the course of two recent flaring events was investigated, making it possible to probe the physical extent and particle composition of the emission region. Evidence was found for flux variability on timescales down to 14 days, suggestive of emission originating very close to the super-massive black hole, and spectral hardening during both flares, perhaps associated with the injection of accelerated particles prior to the detection of an increased flux of ~GeV photons. Given the wider implications of these results for the object class, studies of other cooling core clusters with Fermi-LAT are underway, and will be presented at the meeting.

Fluid jet model of blazars

Author: William Potter

University of Oxford

Co-Authors: G.Cotter (University of Oxford)

Session: EXP: Explosive transients, AGNs and black holes

Presentation type: Poster

Summary:

I present the findings of my work on an adiabatic fluid jet model for blazars. This includes a thorough treatment of inverse-compton scattering from synchrotron radiation from the same population of electrons and from CMB and accretion disc seed photons. The jet is modelled as an axisymmetric adiabatic fluid expanding with a constant opening angle. The model reproduces observed blazar properties including the flat radio spectrum, synchrotron and inverse-compton peaks and also flaring of the inverse-compton emission induced by flaring of the accretion disc.

High-redshift quasar selection in VIKING

Author: Joseph Findlay

QMUL

Co-Authors:

Session: EXP: Explosive transients, AGNs and black holes

Presentation type: Poster

Summary:

Over the last ten years, optical surveys such as the Sloan Digital Sky Survey and the Canada-France High-redshift Quasar Survey have increased the number of known quasars at z ~ 6 to over 50. The key to the photometric selection of a strong quasar candidate is to isolate the characteristic absorption break blueward of the Lyman alpha transition brought about by intervening HI. At z > 6 Lyman-alpha begins to shift out of the Sloan z' band and into the near-IR. While progress towards higher redshifts is possible in a predominantly optical parameter space (e.g. PanStarrs) faint optical detections make it difficult to reject the numerous Galactic stars with scattered quasar like colours that out number high-z quasars by a factor ~ 10^4. To this end a number of other surveys have taken a different approach, employing the near-IR as their selection space, a tactic which has had recent encouraging success in e.g. UKIDSS. The ESO public VISTA Kilo-degree Infrared Galaxy survey (VIKING) is another near-IR based survey that is nearing its first public data release. VIKING's combination of depth and area is ideally suited for quasar searches at the highest redshifts. Here I will introduce the VIKING survey and the numerous motivations for discovering quasars beyond z ~ 6. I will then look at the detailed selection processes involved in isolating the strongest candidates for follow-up from the large number of false positives occupying the VIKING quasar selection space.

Observing with Swift

Author: Julian Osborne

University of Leicester

Co-Authors: Andrew Beardmore, Phil Evans, Christopher Mountford, Paul O'Brien, Claudio Pagani, Kim Page (University of Leicester)

Session: EXP: Explosive transients, AGNs and black holes

Presentation type: Poster

Summary:

Swift is a sensitive hard X-ray, X-ray, UV and visual band observatory with open access to both pre-planned and rapid-response target-of-opportunity proposals. TOOs of a few kiloseconds observing time can at a few hours to days notice, with the data delivered within hours. Larger proposals may be submitted to the annual Guest Investigator program (which this year will allow proposals of >100 targets or >100 ksec). Support for proposers is available from the UK Swift Science Data Centre (http://www.swift.ac.uk/). Astronomers are encouraged to make use of this valuable observing facility, which is easy to use, quick to respond, and for which support is available.

Results from the Swift Supergiant Fast X-ray Transients Project

Author: Claudio Pagani

University of Leicester

Co-Authors: P. Romano (INAF-IASF Palermo), P.A. Evans (UL), K.L. Page (UL), on behalf of the Swift SFXT Project

Session: EXP: Explosive transients, AGNs and black holes

Presentation type: Poster

Summary:

Supergiant Fast X-ray Transients (SFXTs) are a class of High Mass X-ray Binaries, first discovered by the INTEGRAL satellite, characterized by their short outburst emission and the association with blue supergiant companions. The Swift satellite is uniquely and ideally suited to study SFXTs thanks to its sensitivity, the broadband coverage and its scheduling flexibility. We illustrate here the main results from the observing campaigns on SFXTs performed by Swift during the last four years. The monitoring allowed, for the first time, the study of the onset of an outburst, and the broadband modelling of the outburst emission; it showed that the outburst events are longer than previously measured by INTEGRAL and led to the discovery of X-ray emission during an intermediate state of low accretion outside of outburst. The Swift monitoring has given insights into the source of the observed emission and the mechanisms that trigger the system outbursts.

The optical counterpart to the hyperluminous X-ray source HLX1

Author: George Hau

ESO

Co-Authors: R. Soria (MSSL)

Session: EXP: Explosive transients, AGNs and black holes

Presentation type: Poster

Summary:

The existence of intermediate-mass black holes (IMBHs)-- black holes of masses between 1 thousand and 1 million solar masses -- has important implications for the formation and evolution of star clusters and supermassive black holes. The hyperluminous X-ray source HLX1 located in the S0 galaxy ESO 243-49 (Soria et al 2010, Farrell et al 2010) represents one of the strongest candidates for their existence. We have performed deep VLT/VIMOS UBVRI photometry of HLX1 and its host star cluster. I will present the latest analysis on the stellar populations of the host cluster, the constraints on the nature of HLX1, and examine the connection between HLX1 and the host galaxy.

Dynamics in the solar atmosphere due to emerging flux observed by Hinode and SDO

Author: David Shelton

MSSL/UCL

Co-Authors: Professor L.Harra Doctor L. Green

Session: FLU: Flux emergence and eruptions

Presentation type: Poster

Summary:

Magnetic flux emergence into the solar atmosphere can create violent events such as solar flares, jets and coronal mass ejections as the new flux interacts with the pre-existing field. For the past few years we have been at solar minimum meaning that major flux emergence events which form active regions , and the associated solar activity, has been at a minimum. We are now returning to a period of high activity on the Sun. We present data from the Solar Dynamics Observatory and the EIS instrument on Hinode on an active region present on the solar disk between the 20th October and 30th October 2010. New magnetic flux was observed to emerge into the pre-existing active region over a timesame of 4 days. We present our initial findings of our study into how energy is transferred from below to above the solar surface during this flux emergence event.

Episodic Hard X-ray Bursts in Solar Flares

Author: Aidan O

Trinity College, Dublin

Co-Authors: P.T.Gallagher

Session: FLU: Flux emergence and eruptions

Presentation type: Poster

Summary:

During solar flares, hard X-rays (HXR) are emitted by accelerated electrons interacting with the dense underlying chromosphere. HXR spectra observed during these peaks can be used to calculate the properties of the flaring plasma, such as the density distributions at the time of the peak (e.g., Aschwanden et al. 2002). However, the impulsive nature of HXR bursts and the difficulties associated with HXR imaging-spectroscopy makes this a challenging task. Here, a flare that exhibited multiple separated HXR peaks is described, and used to determine the evolution of the flaring plasma with time. Our results provide new information on the structure of plasma in flaring loops and on the fundamental physics of chromospheric evaporation.

Granular-scale magnetic flux emergence within an emerging active region

Author: Santiago Vargas Dominguez

Mullard Space Science Laboratory (UCL)

Co-Authors: L. van Driel-Geztelyi (MSSL/UCL, Observatoire de Paris, Konkoly Observatory of Hungarian Academy of Sciences)

Session: FLU: Flux emergence and eruptions

Presentation type: Poster

Summary:

In this work we analyze data from the Hinode spacecraft targeting an emerging magnetic flux region.We focus on small-scale events identified by distinctive dark features in CaII H chromospheric filtergrams. Energy release at low chromospheric heights is detected to be boosted by the disappearance of the dark features after they reached their maximum size. The observed phenomena are explained as evidencing elementary flux emergence into the solar atmosphere. We are thus detecting granular-scale arch filament systems, that emerge and interact with pre-existing fields.

High resolution observations of a B-class flare

Author: David Jess

Queen

Co-Authors: P. H. Keys (QUB); R. Milligan (QUB); M. Mathioudakis (QUB)

Session: FLU: Flux emergence and eruptions

Presentation type: Poster

Summary:

On the 29 October 2010, NOAA AR 11117 erupted producing a B2 flare. This event was captured by both the Rapid Oscillations in the Solar Atmosphere (ROSA) and Interferometric BI-dimensional Spectrometer camera systems. Using a range of optical filters, incorporating blue-continuum, H-alpha, Fe I and Sodium D1 observations, we piece together the progression of this low-energy flare at the highest possible spatial, spectral and temporal resolutions.

ASKAP: The Australian SKA Pathfinder

Author: Lisa Harvey-Smith

CSIRO Astronomy & Space Science

Co-Authors:

Session: FUT: Future windows on the Universe

Presentation type: Poster

Summary:

The Australian SKA Pathfinder is an aperture synthesis radio telescope currently under construction at the candidate site for the Square Kilometre Array (SKA) in Western Australia. In this talk I will describe some of the many unique features of ASKAP, including the telescope's focal plane arrays (radio cameras), the novel 3-axis dish steering system and the pristine radio-quiet environment. I will discuss some of the technical challenges these new technologies present and how they are overcome. As the construction of ASKAP is well underway, the latest pictures of recent progress from the site will be shown. Finally, the ASKAP science case will be discussed, in particular the potential for new discoveries in wide-field science and in the largely unexplored time domain.

First e-Merlin Test Images of Faint AGN in GOODS-N

Author: Dr Tom Muxlow

Jodrell Bank Centre for Astrophysics

Co-Authors: Dr Robert Beswick (Jodrell Bank Centre for Astrophysics)

Session: FUT: Future windows on the Universe

Presentation type: Poster

Summary:

As a prelude to the e-MERGE Legacy project, e-Merlin test observations have been made of the central region over a frequency range of 6.0-6.5 GHz utilizing the new wide-bandwidth optical fibre connections and WIDAR correlator. This illustrates the ability of e-Merlin to detect and image weak AGN cores in distant star-forming galaxies.

Future UK access to northern-hemisphere optical telescopes

Author: Chris Benn

Isaac Newton Group, La Palma

Co-Authors: Marc Balcells (Isaac Newton Group)

Session: FUT: Future windows on the Universe

Presentation type: Poster

Summary:

We review recent and possible future changes to the suite of northern-hemisphere optical telescopes accessible to UK astronomers, and consider the likely impact on UK astronomy. In particular, we review the implications for ground-based optical follow-up of space and radio surveys already in the pipeline, for studies of rare objects and events, for instrument development, and for the training of young astronomers.

LOFT (Large Observatory for X-ray Timing)

Author: Awat Rahimi

UCL - MSSL

Co-Authors: S. Zane, R.P. MIgnani, D. Walton, A. Smith, R. Cole, B. Winter, P. Guttridge, D. Kataria, P. Smith, on behalf of the LOFT Science Team

Session: FUT: Future windows on the Universe

Presentation type: Poster

Summary:

LOFT (Large Observatory for X-ray Timing) is one of the four M3 missions that have been selected by ESA for an Assessment Phase with launch in 2020-2022. LOFT is specifically designed to study the very rapid X-ray flux and spectral variability that directly probe the motion of matter down to distances very close to black holes and neutron stars. The 10 m2 Large Area Detector (LAD), with its temporal (a few nsec) and spectral resolution (<260 eV around 6 keV), allows to exploit the relevant astrophysical diagnostics and holds the potential to revolutionise the study of collapsed objects in our galaxy and of the brightest supermassive black holes in active galactic nuclei. We illustrate the scientific goals of the mission and the major role played by the Mullard Space Science Laboratory and UK partner institutes in the LOFT Science Team.

The challenges of high precision spectroscopy

Author: Ulrike Lemke

Durham University

Co-Authors:

Session: FUT: Future windows on the Universe

Presentation type: Poster

Summary:

As telescope apertures increase in size and more sophisticated spectroscopic techniques become available, ever-higher signal-to-noise ratios and spectral resolutions come into reach. This progress will permit fundamental advances in a range of areas. For example, the magnetic field distribution of stellar atmospheres can be analysed with unprecedented precision. Furthermore, using radial velocity methods it will be possible to detect Earth-like planets orbiting host stars similar to the Sun. The optical fibre is a key technology in these developments. However, there are complications to consider when utilising fibres. Phenomena such as incomplete scrambling and modal noise produce temporal instabilities in intensity and central wavelength position of the spectral lines, ultimately limiting the spectrograph performance. I will briefly introduce these phenomena and give an overview of corrective techniques. As far as possible I will furnish estimates that will quantify these effects on astronomical measurements.

The Extragalactic Potential of SPICA and SAFARI

Author: David Clements

Imperial College London

Co-Authors: The SPICA-SAFARI Consortium

Session: FUT: Future windows on the Universe

Presentation type: Poster

Summary:

SPICA is the next generation space far-infrared space telescope and will follow on from the great success of Herschel. It will be a Japanese-led mission with ESA participation and a European instrument. SPICA will have a 3m class telescope with mechanically cooled instruments and telescope primary. This will allow a greater mission lifetime and, with the primary at ~10 times lower temperature than that of Herschel, much greater sensitivity. Essentially for anything that Herschel can detect in the continuum, SPICA-SAFARI will be able to obtain a spectrum. In this presentation we discuss the huge potential for extragalactic astronomy of SPICA and the European SAFARI far-IR imaging-spectrometer instrument.

12CO lines and LVG Model: NGC6946

Author: Selcuk Topal

Oxford Physics

Co-Authors: E.Bayet (Oxford Astrophysics), M.Bureau (Oxford Astrophysics)

Session: GAL: Physics of galaxies at high and low redshift (includes Milky Way)

Presentation type: Poster

Summary:

The understanding of molecular gas properties is essential to better constrain star formation processes in external galaxies. To determine the gas kinetic temperature (Tk), volume density (n(H2 )) and column density (N(CO)) of the molecular gas using non-local thermodynamic equilibrium models, it is necessary to obtain observations of multiple lines of 12CO. We present such a survey in the nearby galaxy NGC 6946, that includes a very high number of supernovae and has a star formation rate 10-15 times higher than our own Galaxy. We focus on two specific positions in spiral arms that covers three prominent star formation regions. We use the Leiden Atomic and Molecular Database for the collision rates and coefficients, the RADEX code for large velocity gradient (LVG) model calculations, and we apply χ2 tests to choose the best models. We present our LVG model results for the two positions using at least four 12CO transitions, and also the radial distribution of molecular gas up to 5.6 kpc from the center using multiple pointings along a radial cut. Both positions include very warm and dense gas.

A multi-wavelength study of AGN feedback in BCG

Author: Stephen Hamer

Durham University

Co-Authors: A.C.Edge (Institute for Computational Cosmology, Department of Physics, University of Durham, South Road, Durham DH1 3LE, UK) A.M.Swinbank (Institute for Computational Cosmology, Department of Physics, University of Durham, South Road, Durham DH1 3LE, UK)

Session: GAL: Physics of galaxies at high and low redshift (includes Milky Way)

Presentation type: Poster

Summary:

Brightest Cluster Galaxies have a central role in the regulation of cooling gas within the cores of clusters through an AGN feedback. This feedback mechanism is currently believed to be the main component preventing catastrophic cooling of gas within cluster cores. I will present multi-wavelength observations of Hydra-A and discuss the presence of a rotating disc within the BCG and central cluster region. The existence of this ordered rotation and its potential effects on AGN feedback within the BCG and cluster core will be discussed. I will also outline similar, though less complete, observations of a larger sample of BCGs and discuss how our results suggest that the processes evident in Hydra-A may be an important step in understanding the link between the cooling gas and the AGN at the centre of every BCG.

A multi-wavelength view of Star Formation in Nearby Galaxies

Author: Smriti Mahajan

UNIVERSITY OF BIRMINGHAM

Co-Authors: Matthew L.N. Ashby, Steven P. Willner, Giovanni G. Fazio (CfA); Somak Raychaudhury (University of Birmingham)

Session: GAL: Physics of galaxies at high and low redshift (includes Milky Way)

Presentation type: Poster

Summary:

We report the first outcomes from the Star Formation Reference Survey, a program designed to systematically elucidate the properties of nearby star forming galaxies. By controlling for total and specific star formation rate together with dust temperature, we have assembled a large (369) far infrared (FIR)-selected sample that is fully representative of all conditions under which star formation occurs in the local Universe. A rich dataset spanning multiple bands from the ultraviolet to the mid-infrared and into the radio is now being used to assess the reliabilty and systematics of the star formation rate (SFR) indicators commonly used in the literature. In this talk we show how SFR distributions derived from mutually independent data correlate with one another and with the total bolometric luminosity of the galaxy. Our results suggest that the global SFR for galaxies (spanning over five orders in luminosity) as expected from their bolometric luminosity can be derived using any single star formation tracer (FIR, 8.0 micron dust, FUV, NUV or 1.4 GHz radio continuum emission) within a factor of 1.5-4, such that the scatter in the correlation is a function of luminosity and galaxy type.

A New Method to Determine the Star Formation Histories of Resolved Galaxies

Author: Emma Small

Liverpool John Moores University

Co-Authors: Dr. David Bersier (Liverpool John Moores University) Dr. Maurizio Salaris (Liverpool John Moores University)

Session: GAL: Physics of galaxies at high and low redshift (includes Milky Way)

Presentation type: Poster

Summary:

Resolved stellar populations in the Local Group enables the study of galaxy formation and evolution over cosmic time. In this talk, I will present a new maximum likelihood method to determine the complex star formation histories of stellar populations by fitting combinations of isochrones to a colour-magnitude diagram. The aim of the method is to determine the ages, metallicities, distance and reddening of the stellar population consistently and objectively. I will discuss tests completed using synthetic data to show the robustness of the technique and present results for the star formation history of the Carina dwarf galaxy.

A numerical/theoretical study of triggered star-formation

Author: SUMEDH ANATHPINDIKA

INDIAN INSTITUTE OF ASTROPHYSICS

Co-Authors:

Session: GAL: Physics of galaxies at high and low redshift (includes Milky Way)

Presentation type: Poster

Summary:

The lifetime of molecular clouds (MCs) is typically of the order of a million years. MCs over this period, may be exposed to catastrophic events such as collision with other clouds, irradiation by a flux of ionising photons emitted by young OB stars, or possible interaction with dense shells driven by supernovae or shells associated with HII regions. In this talk, I propose to review my recent work on the possible outcome of these realisations with the aid of numerical simulations performed using the powerful particle-based, Lagrangian scheme, smoothed particle hydrodynamics (SPH).The simulations demonstrate that, commencing from a relatively quiescent cloud, an external trigger, as one of those listed above, could produce fractal structure in its interiors; stars could possibly form in the densest filamentary regions. While intercloud collisions are dissipative, I argue, evolution of the post-collision composite body depends on the precollision velocity of individual clouds. I also suggest that the relatively denser MCs irradiated by ionising radiation could be good demonstrative candidates of sequential star-formation, a scenario proposed by Elmegreen and others more than three decades ago. Finally I shall describe the spectrum for clumps condensing out of shocked gas slabs.

Analysing stellar motions and spiral arm formation in spiral galaxies

Author: Robert Grand

Mullard Space Science Laboratory (UCL)

Co-Authors: Daisuke Kawata, Mark Cropper

Session: GAL: Physics of galaxies at high and low redshift (includes Milky Way)

Presentation type: Poster

Summary:

Spiral density wave theory (SDWT) states that the spiral pattern is a long lived wave structure, in that a spiral arm is analogous to the crest of a wave in the ocean; not necessarily consisting of the same stars as it evolves, but maintaining the high density of a wave peak. It also states that the spiral arms rotate at fixed (pattern) speeds, constant over radius and time. We run several N-body simulations of Milky Way size disk galaxies, and study how spiral arms develop and affect the motions of stellar particles throughout their lives. We find that the spiral arms are recurrent material features, and the pattern speed generally decreases with radius, in such a way that the pattern speed almost equals the rotation speed of stars at all radii. We demonstrate that such spiral arms induce strong radial migration of the stellar component and discuss how the orbits of stars are related to the recurrent nature of the spiral arms.

Anatomy of an early-type minor merger: a WFC3 and SAURON study of NGC 4150

Author: Sugata Kaviraj

Imperial College London

Co-Authors: R. M. Crockett (University of Oxford); R. W. O'Connell (University of Virginia); J. Silk (University of Oxford); R. Windhorst (Arizona State University); B. Whitmore (Space Telescope Science Institute); M. Cappellari (University of Oxford); M. Bureau (University of Oxford); R. L. Davies (University of Oxford); S. K. Yi (Yonsei University)

Session: GAL: Physics of galaxies at high and low redshift (includes Milky Way)

Presentation type: Poster

Summary:

A significant recent discovery, using ultraviolet (UV) survey data, is the widespread presence of low-level star formation in nearby early-type galaxies (ETGs), plausibly driven by gas-rich minor mergers. Combining the unprecedented UV capabilities of HST’s new Wide Field Camera 3 (WFC3) with integral-field spectroscopy from SAURON, we perform a detailed, spatially-resolved analysis of young stars and their kinematics in NGC 4150, a nearby star-forming ETG. A 'pixel-by-pixel' analysis in five WFC3 filters, spanning UV to i-band, reveals a central 0.9 Gyr old young stellar population, with a median metallicity of 0.5 solar, that contributes 3% of the stellar mass and is created by a minor merger with a mass ratio of ~1:20. Comparison to the SAURON kinematics demonstrates that the young stars also form a kinematically-decoupled core in the central 1/4 Re of the galaxy. While survey data has quantified the broad characteristics of star formation in the ETG population, spatially-resolved analyses, such as the one presented here, can strongly constrain the star formation and kinematical evolution on a galaxy-by-galaxy basis, making them highly desirable for a thorough understanding of ETGs at late epochs. This work was the subject of a recent Hubble press release: http://hubblesite.org/newscenter/archive/releases/2010/38/.

Attractors in phase-space of stellar systems under impulses

Author: Jeremy Barber

University of St. Andrews

Co-Authors: H. Zhao (University of St. Andrews); X. Wu (Max Planck Institute)

Session: GAL: Physics of galaxies at high and low redshift (includes Milky Way)

Presentation type: Poster

Summary:

We examine the effects for impulses on to a star cluster or a galaxy via controlled N-body simulation, and examine if they converge to fixed points in certain space of dynamical parameters independent of initial condition and the assumption of the gravity theory. We check especially the finding of Hansen et al. (2010) that the final states all live on a narrow line in the radial pressure gradient vs. anisotropy plane. We vary the recipes for impulses to examine if there are multiple attractors.

Build it up, tear it down: Star formation in the Galactic centre

Author: W. E. Lucas

University of St Andrews

Co-Authors: I. A. Bonnell (University of St Andrews)

Session: GAL: Physics of galaxies at high and low redshift (includes Milky Way)

Presentation type: Poster

Summary:

Observations of the Galaxy’s centre have revealed the existence of two discs or possibly streamers of O and W-R stars orbiting Sgr A* at radii between about 0.05 and 0.5 pc and at an angle approaching 90° to one another. This would seem to indicate that two separate star-forming events have taken place around the black hole, yet the stars appear to be coeval which points instead to a single event – something of a problem. Here we use smoothed particle hydrodynamics (SPH) to show it is possible to create two star-forming gaseous discs at large angles from one another from a single turbulent cloud.

Chemodynamical evolution of M33 size disk galaxies

Author: Awat Rahimi

UCL - MSSL

Co-Authors: Daisuke Kawata

Session: GAL: Physics of galaxies at high and low redshift (includes Milky Way)

Presentation type: Poster

Summary:

We are developing a new version of GCD+, an N-body/SPH chemodynamical code, to include powerful supernovae feedback and metal diffusion and new star formation and feedback recipes to keep the gas and stellar particle masses equal and constant. We simulate M33-size galaxies, and compare them with recent multi-wavelength observations. We set up an initial condition of an M33-like galaxy that comprises gas and stellar disk particles in a fixed dark matter halo gravitational potential. The simulations then follow about 2 billion years of evolution and include the effects of radiative cooling, star formation and chemical evolution. We discuss how the star formation rate, metallicity distribution and velocity dispersion of the gas components are affected by the modelling of star formation and feedback, comparing with recent observations.

Chemodynamical evolution of M33 size disk galaxies

Author: Awat Rahimi

UCL - MSSL

Co-Authors: Daisuke Kawata

Session: GAL: Physics of galaxies at high and low redshift (includes Milky Way)

Presentation type: Poster

Summary:

We are developing a new version of GCD+, an N-body/SPH chemodynamical code, to include powerful supernovae feedback and metal diffusion and new star formation and feedback recipes to keep the gas and stellar particle masses equal and constant. We simulate M33-size galaxies, and compare them with recent multi-wavelength observations. We set up an initial condition of an M33-like galaxy that comprises gas and stellar disk particles in a fixed dark matter halo gravitational potential. The simulations then follow about 2 billion years of evolution and include the effects of radiative cooling, star formation and chemical evolution. We discuss how the star formation rate, metallicity distribution and velocity dispersion of the gas components are affected by the modelling of star formation and feedback, comparing with recent observations.

Evolution of high redshift galaxies, QSOs and sub-mm sources

Author: Tom Shanks

Durham University

Co-Authors: M.D. Hill (Durham University); N. Metcalfe (Durham University); N. Nikoloudakis (Durham University)

Session: GAL: Physics of galaxies at high and low redshift (includes Milky Way)

Presentation type: Poster

Summary:

We argue that the phenomenology of galaxy and QSO evolution may be simpler when separated from the expectations of theoretical modelling. Thus we first use the COSMOS field photo-z of Ilbert et al (2009) to test the galaxy pure luminosity evolution model of Metcalfe et al (1996). We find good agreement between this model's predictions and the luminosity functions of red and blue galaxies out to z=2. This implies that early types have only passively evolved over this look-back time while the surface brightness of late types has brightened significantly but with little impact of galaxy merging in either case. We next suggest that the lack of early-type evolution taken together with the luminosity independence of QSO clustering and the pure luminosity evolution of the QSO LF may imply that QSOs are long-lived and that the prime epoch of black-hole growth was at z>2. Finally, we show that this simple picture of galaxy and QSO evolution can also accurately predict number count and redshift distributions in the X-ray, Spitzer, Herschel and SCUBA bands. We briefly discuss the implications for theoretical galaxy formation models.

Galaxy And Mass Assembly: Independent Caustic Mass Measurements

Author: Mehmet Alpaslan

University of St Andrews

Co-Authors: A. Robotham (University of St Andrews); S. P. Driver (University of Western Australia)

Session: GAL: Physics of galaxies at high and low redshift (includes Milky Way)

Presentation type: Poster

Summary:

In this work, we use the caustic mass estimator to measure the dynamical masses of the GAMA groups. We will also compare these mass estimates to those obtained through a dynamical analysis of the groups.

In search for new bulge classification scheme

Author: Christina Gao

Oxford University

Co-Authors: I.K.Soechting (University of Oxford); A.E.Sansom (University of Central Lancashire)

Session: GAL: Physics of galaxies at high and low redshift (includes Milky Way)

Presentation type: Poster

Summary:

In this investigation we studied a sample of 42 nearby galaxies with their g- and r- band images obtained with the GMOS instruments at the Gemini Observatory. We used Galfit 3.0, a two-dimensional fitting tool, to model the surface brightness profile and simultaneously decompose the bulge and disk for each galaxy. We found that the conventional bulge-disk structure did not apply to every single galaxy in our sample and that some of the galaxies required a double bulge fitting at the centre. The results imply that a simple division into bulges and pseudo-bulges might not reflect the true complexity of bulge morphologies. Our sample also benefits from the high signal-to-noise spectra, which will allow us, in the future, to cross examine our findings with the metallicity and age distribution.

Investigations of dust heating in M81, M83, and NGC 2403 with Herschel and Spitzer

Author: George Bendo

University of Manchester

Co-Authors: Herschel-SPIRE Local Galaxies Guaranteed Time Program

Session: GAL: Physics of galaxies at high and low redshift (includes Milky Way)

Presentation type: Poster

Summary:

We use Herschel Space Observatory and Spitzer Space Telescope 24-500 micron data along with ground-based optical and near-infrared data to understand how dust heating in the nearby face-on spiral galaxies M81, M83, and NGC 2403 is affected by the starlight from all stars and by the radiation from star forming regions. We find that 70/160 micron flux density ratios tend to be more strongly influenced by star forming regions. However, the 160/250, 250/350, and 350/500 micron flux density ratios are more strongly affected by the light from the total stellar populations, suggesting that the dust emission at >160 microns originates predominantly from a component that is colder than the dust seen at <160 microns and that is relatively unaffected to star formation activity. We conclude by discussing the implications of this for modelling the spectral energy distributions of both nearby and more distant galaxies and for using far-infrared dust emission to trace star formation.

Line Contamination in the SCUBA-2 Continuum Data

Author: Emily Drabek

University of Exeter

Co-Authors: J. Hatchell (University of Exeter)

Session: GAL: Physics of galaxies at high and low redshift (includes Milky Way)

Presentation type: Poster

Summary:

Observations of the dust emission using bolometer arrays can be contaminated by molecular line flux, such as the flux from 12CO. It is important to quantify the contribution of CO flux to the continuum flux in order to distinguish between observations of fainter objects with higher sensitivity detectors and contamination to the dust continuum bands due to molecular lines. The conversion factors for CO line integrated intensities were calculated for the SCUBA-2 bands and applied to HARP 12CO maps of ngc1333 in the Perseus complex in order to calculate the contribution of CO to the dust continuum.

Mapping The Outer Galaxy in CO and HI

Author: Lee Summers

Co-Authors: C. M. Brunt (University of Exeter)

Session: GAL: Physics of galaxies at high and low redshift (includes Milky Way)

Presentation type: Poster

Summary:

Using observations of the J=1-0 transition of CO from the Exeter-FCRAO Galactic Plane Survey and 21cm HI observations, from the Canadian and VLA Galactic Plane surveys, of the first and second Galactic quadrants of the Milky Way - I present a model of spiral structure (involving the Perseus and Outer spiral arms) with spatially convolved and resampled maps of these spiral arm regions, at constant linear resolution.

On the Origins of Compact Elliptical Galaxies

Author: Avon Huxor

University of Bristol

Co-Authors: S.Phillipps (Bristol); J.Price (Bristol)

Session: GAL: Physics of galaxies at high and low redshift (includes Milky Way)

Presentation type: Poster

Summary:

Compact elliptical (cE) galaxies are a rare type, exemplified by M32, exhibiting small effective radii and high mean surface brightnesses. Recent work has suggested that the most likely scenario for the formation of cEs is as a result of the tidal stripping of a more massive disk galaxy. Others, however, argue that they represent the low-mass end of the population of normal elliptical galaxies. We have undertaken a survey of SDSS DR7 (with follow-up observations) to identify cE candidates across a range of environments to try and address this issue. In this paper I will present two newly-found cEs in which we see the stripping in progress. "the smoking gun" of the stripping scenario. It is notable that both of these galaxies are found in very small galaxy groups, not the galaxy clusters in which cE have, for the most part, been hitherto sought. However, we have also found one example of an isolated cE, with no evidence of any disk or tidal features. It can not be the result of stripping, and may be a genuine low-mass elliptical. These three cEs show that at least two channels of formation are available.

Planck Early Results: New Light on Anomalous Microwave Emission from Spinning Dust Grains

Author: Michael Peel

Jodrell Bank C. for Astrophysics, University of Manchester

Co-Authors: Planck collaboration: Ade et al.

Session: GAL: Physics of galaxies at high and low redshift (includes Milky Way)

Presentation type: Poster

Summary:

The Planck collaboration have recently announced the first science results from the mission, looking at foreground emission from our Galaxy. This talk will summarise the results from the first Planck science paper on Anomalous Microwave Emission (AME). Planck has revealed the high frequency part of the AME spectrum from the Perseus and Rho Ophiuchus molecular clouds for the first time, and found that the most precise measurements to date of this effect are well fitted using spinning dust grain models. This is a new emission mechanism that has been discovered in the last 15 years, which peaks at wavelengths of around 1cm (30GHz). In Perseus, spinning dust in the dense molecular gas can account for most of the AME; the low density neutral gas appears to play a minor role. In Rho Ophiuchus, the ~30 GHz peak is dominated by dense molecular gas, but there is an indication of an extended tail at frequencies 50-100 GHz, which can be accounted for by irradiated low density atomic gas. The discovery of two new regions of AME from a search of the Planck 28.5GHz map was also reported, which were again well fitted by spinning dust models.

Radiative transfer modelling of galaxies in the epoch of SPICA

Author: Dr. Cristina C. Popescu

University of Central Lancashire

Co-Authors: Richard J. Tuffs (Max Planck Institut fuer Kernphysik, Heidelberg, Germany) and the SPICA/SAFARI consortium

Session: GAL: Physics of galaxies at high and low redshift (includes Milky Way)

Presentation type: Poster

Summary:

We are living in an era of ever better and deeper wide-field optical surveys which have revealed a large population of translucent systems - the population of normal spiral galaxies. However, the majority of the spiral galaxies seen in these surveys do not have information on dust emission, which is essential for a complete characterisation of these systems. Here we highlight the huge potential of the next generation Space Infrared Telescope for Cosmology and Astrophysics (SPICA) in detecting statistical samples of local Universe low luminosity spiral galaxies. We also report on recent progress on radiative transfer modelling of these galaxies, which is a prerequisite for deriving intrinsic physical parameters from their panchromatic spectral energy distributions.

Studying the influence of magnetic fields in star formation with BLAST-Pol

Author: Lorenzo Moncelsi

Cardiff University

Co-Authors: P. Ade (Cardiff), F. E. Angile (UPenn), S. Benton (UToronto), E. Chapin (UBC), M. Devlin (UPenn), L. Fissel (UToronto), N. Gandilo (UToronto), J. Gundersen (UMiami), P. Hargrave (Cardiff), D. Hughes (INAOE), J. Klein (UPenn), A. Korotkov (Brown), G. Marsden (UBC), T. Matthews (NorthWestern), T. Mroczkowski (UPenn), B. Netterfield (UToronto), G. Novak (NorthWestern), D. Nutter (Cardiff), L. Olmi (U. Puerto Rico/INAF), E. Pascale (Cardiff), C. Quinn (Cardiff), G. Savini (UCL), D. Scott (UBC), J. Shariff (UToronto), J. Soler (UToronto), N. Thomas (UMiami), M. Truch (UPenn), C. Tucker (Cardiff), G. Tucker (Brown), D. Ward-Thompson (Cardiff), D. Wiebe (UBC).

Session: GAL: Physics of galaxies at high and low redshift (includes Milky Way)

Presentation type: Poster

Summary:

The Balloon-borne Large Aperture Submillimeter Telescope for Polarimetry (BLAST-Pol) is a suborbital mapping experiment, designed to study the role played by magnetic fields in the earliest stages of star formation, via the polarised submillimetre emission from aligned elongated dust grains. BLAST-Pol is the reconstructed BLAST telescope, with the addition of linear polarisation capabilities. Using a 1.8m Cassegrain telescope, BLAST-Pol images the sky onto a focal plane of 280 bolometric detectors in three arrays at 250, 350, and 500 um, with a resolution of 30'' at 250 um. BLAST-Pol has just completed its first successful 10-day flight from Antarctica in December 2010, observing a dozen of Galactic molecular clouds with unprecedented combined mapping speed and resolution. The instrument provides a much needed bridge in spatial coverage between larger-scale, coarse resolution surveys and narrow field of view, high resolution observations of substructure within molecular cloud cores. The larger scale surveys in the optical/near-infrared measure absorption polarisation and hence only trace the low-extinction (Av~1-5), low-density edge regions of molecular clouds, while ground-based submillimetre polarimetry is only sensitive to the high-extinction (Av~10-100), high-density central regions of the clouds. BLAST-Pol is sensitive enough to detect polarised emission over a wide range of dust column densities, corresponding to Av >= 4.

The Effect of the Large Scale Structure of the Galaxy on Star Formation Properties

Author: David Eden

Liverpool John Moores University

Co-Authors: T.J.T.Moore (Liverpool John Moores University)

Session: GAL: Physics of galaxies at high and low redshift (includes Milky Way)

Presentation type: Poster

Summary:

The Galactic plane at l=30° contains the tangent of the Scutum-Centaurus Arm and the near end of the Long Bar of the Galaxy. The Sagittarius Arm also runs across the field. We make use of the BOLOCAM Galactic Plane Survey and the Galactic Ring Survey to find the fraction of total gas mass in dense, 1.1mm continuum traced structures and to see how this fraction varies over this field; in relation to the proximity of large-scale structures and the local environment.

The effects of dust on the derived photometric parameters of disks and bulges in spiral galaxies

Author: Bogdan Adrian Pastrav

Jeremiah Horrocks Institute-University of Central Lancashire

Co-Authors: Cristina C. Popescu (Jeremiah Horrocks Institute-University of Central Lancashire), Richard J. Tuffs (Max Planck fur Kernphysik-Heidelberg), Anne E. Sansom (Jeremiah Horrocks Institute-University of Central Lancashire)

Session: GAL: Physics of galaxies at high and low redshift (includes Milky Way)

Presentation type: Poster

Summary:

Here we quantify the effects of dust on the derived photometric parameters of disks and bulges: disk scalelengths, central surface-brightness, axial ratios and bulge effective radii. The effects of dust are derived for both broad-band and narrow line (Balmer lines) images. The changes in the derived photometric parameters from their intrinsic values (as seen in the absence of dust) were obtained by fitting simulated images of disks and bulges produced using radiative transfer calculations and the model of Popescu et al (2011). This study follow on the analysis of Moellenhoff et al. (2006), who quantified the effects of dust on the photometry of old stellar disks seen at low and intermediate inclination. Here we extend the study to disks at all inclinations and we also investigate the changes in the photometry of young stellar disks and bulges. We find that dust effects on all structural parameters of disks and bulges are significant and strongly increase with inclination and dust opacity.

The Exeter-FCRAO Carbon Monoxide Survey of the Northern Galactic Plane

Author: Lee Summers

Co-Authors: C. M. Brunt (University of Exeter) J. C. Mottram (University of Exeter) M. H. Heyer (University of Massachusetts)

Session: GAL: Physics of galaxies at high and low redshift (includes Milky Way)

Presentation type: Poster

Summary:

Large scale Carbon Monoxide (CO) observations help us understand the structure and dynamics of the mass reservoir available for Galactic star formation. We observed the J(1-0) lines of 12CO and 13CO over a wide-latitude region between 141

The Halo Occupation Distribution since z=1.5

Author: Chris Collins

Liverpool John Moores University

Co-Authors: Diego Capozzi (LJMU); John Stott (Durham); Matt Hilton (Nottingham)

Session: GAL: Physics of galaxies at high and low redshift (includes Milky Way)

Presentation type: Poster

Summary:

We study the evolution of the Luminosity Function and Halo Occupation Distribution in 15 X-ray clusters between z=0.8-1.5 using Subaru near-IR imaging. We find that K* evolution is consistent with the semi analytic predictions of Bower et al (2006), with K* about 0.5 mag brighter than the corresponding field data. Both the counts of galaxies in clusters (N_) and the average cluster concentration index c_g=2.8+-pm0.9 of our sample agree with estimates of the same quantities from the Bower et al (2006) predictions, based on our own analysis of these well-matched mock clusters. This indicates that the current semi-analytic models provide an adequate description of the star formation and mass assembly history of most massive cluster galaxies at z=1. Further studies, particularly of the concentration parameter, are required at low and intermediate redshifts (z~0.5), where current datasets disagree.

The molecular gas properties as a function of galaxy activity

Author: Dr Estelle Bayet

University of Oxford

Co-Authors: M. Bureau (University of Oxford) S. Viti (UCL) D. Williams (UCL) A. Crocker (University of Massachusetts)

Session: GAL: Physics of galaxies at high and low redshift (includes Milky Way)

Presentation type: Poster

Summary:

The molecular gas physical properties namely its temperature, its volume gas density, etc as much as the molecular gas chemical properties such as the abundance ratio existing between its observed species, its state of ionisation, etc, are an essential knowledge to acquire for better understanding the process of star formation in external galaxies. So far, only few studies provide a comprehensive determination an analysis of such properties, most often performed at low resolution. With the forthcoming ALMA Interferometer which will help us reaching spatial scales in external galaxies up to a few pc, typical size of individual clouds, it is primordial to pursue and enhanced this effort . I will present in my talk the physical and chemical gas properties that I have obtained at low resolution for a sample of 10 nearby galaxy centers, showing the influence of the various type of galaxy activity or environmental characteristics on these properties i.e. starburst (SB), AGN, SB+AGN, Supernovae, low-metallicity, etc. I will also present for the first time some high-resolution maps recently acquired on a close galaxy (IC10) which starts unveiling the properties of the molecular gas at smaller scales. I will also present for the first time the physical properties obtained for the molecular gas observed in early-types galaxies, galaxies previously thought wrongly to be 'red-and-dead' systems in terms of star formation. I will conclude by enumerating the remaining interesting questions yet to be solved.

The stability of low surface brightness disks based on multi-wavelength modeling

Author: john MacLachlan

University of St Andrews

Co-Authors: L.D. Matthews (Harvard-Smithsonian Center for Astrophysics); K. Wood (University of St Andrews); J.S. Gallagher (University of Wisconsin)

Session: GAL: Physics of galaxies at high and low redshift (includes Milky Way)

Presentation type: Poster

Summary:

To investigate the structure and composition of the dusty interstellar medium (ISM) of low surface brightness (LSB) disk galaxies, we have used multiwavelength photometry to construct spectral energy distributions for three low-mass, edge-on LSB galaxies (Vrot= 88 to 105 km/s). We use Monte Carlo radiation transfer codes that include the effects of transiently heated small grains and polycyclic aromatic hydrocarbon molecules to model and interpret the data. Our results indicate that unlike the high surface brightness galaxies previously modeled, the dust disks appear to have scaleheights equal to those of the stellar disks. This result supports the findings of previous studies that low mass disk galaxies have larger dust scale heights and suggests that the cold ISM of low mass, LSB disk galaxies is stable against fragmentation and gravitational collapse along spiral arms. This may help to explain the lack of observed dust lanes in edge-on LSB galaxies and their low current star formation rates.

The Tully-Fisher Relation of Early-Type Galaxies

Author: Martin Bureau

University of Oxford

Co-Authors: T.A.Davis (University of Oxford); M.J.Williams (University of Oxford); Michele Cappellari (University of Oxford)

Session: GAL: Physics of galaxies at high and low redshift (includes Milky Way)

Presentation type: Poster

Summary:

The Tully-Fisher (luminosity-rotation velocity) relation of disk galaxies is commonly used to provide constraints on their formation and evolution. Unusually, we focus here on early-type galaxies, with significant pressure support. First, based on stellar kinematics and near-infrared imaging, we present detailed stellar dynamical models of a sample of 14 lenticular (S0) and 14 spiral galaxies, yielding both stellar and dynamical mass-to-light ratios. The observed Tully-Fisher relation of the S0 galaxies is found to be 0.5 magnitudes fainter than that of spirals at K-band, and unexpectedly this difference persists when the modeled dynamical masses are used. This implies that lenticular galaxies are not simply faded spirals (the most popular hypothesis), and that they must be 20% more compact at a given rotation velocity. Second, we show that CO is an excellent tracer of the rotation velocity in the numerous molecular gas-rich early-type galaxies. This allows to measure the Tully-Fisher relation of early-types in a straightforward manner, bypassing time-consuming stellar observations and modeling. The observed CO Tully-Fisher relation is consistent with the stellar one, but extends its applicability to all early-type galaxies with significant specific angular momentum (fast-rotators), including elliptical galaxies. Equally important, using the new generation of mm/sub-mm telescopes (e.g. ALMA), the CO Tully-Fisher relation offers a new simple tool to probe the mass-to-light ratio evolution of early-type galaxies to high redshifts.

The VLT LBG Survey

Author: Rich Bielby

Durham University

Co-Authors: T. Shanks (Durham University), P. Tummuangpak (Durham University), N. Crighton (MPIA), L. Infante (Pontifica Universidad Catolica de Chile)

Session: GAL: Physics of galaxies at high and low redshift (includes Milky Way)

Presentation type: Poster

Summary:

We have completed the largest spectroscopic survey of Lyman-break galaxies (LBGs) to date using the wide field of VLT VIMOS. In total, the survey consists of over 2,000 galaxy redshifts over the range 23 quasars). In addition we have complimented the VLT data with AAOmega spectra of R<22 z>2 QSOs in each of our survey fields. Using the LBG spectra, we find evidence confirming the outflowing nature of the gas within LBGs via the offsets (~600km/s) in the emission and absorption rest-frame UV lines. Further to this, we use the LBG data to investigate the large scale structure at z = 3 via the galaxy auto-correlation function, finding an LBG clustering strength of r0 = 3.19 h-1 Mpc, equivalent to these galaxies residing in dark matter halos of mass M ~ 10^11 Msolar. Finally, we combine the LBG redshift and QSO absorption line data to investigate the relationship between gas and galaxies at z=3 and find evidence for the correlation of LBGs with increased densities of HI and CIV.

Using Diffuse Interstellar Bands to Probe the Diffuse Interstellar Medium

Author: Mandy Bailey

Keele University

Co-Authors: J. Th. van Loon (Keele)

Session: GAL: Physics of galaxies at high and low redshift (includes Milky Way)

Presentation type: Poster

Summary:

Typically the Interstellar Medium (ISM) conditions are probed via lines arising from neutral or singly-ionized atoms or molecules. This poses a problem with understanding the nature of gas in high temperature environments such as the Local Bubble (LB) and environments of high ultraviolet radiation such as the Disc-Halo interface. To overcome these problems it is necessary to probe the ISM using species that may survive such conditions. This can be achieved using absorption in the so-called Diffuse Interstellar Bands (DIBs) whose carriers are large molecules such as polycyclic aromatic hydrocarbons (PAHs). Such molecules are thought to be resistant to UV radiation. Observations of DIBs have shown that they are sensitive to their environment with some known to exist in hot, UV-irradiated environments. The ratio of λ5780/ λ5797 equivalent widths is an indicator of the ionization conditions, with a high λ5780/ λ5797 ratio indicating the existence of interfaces between cool/warm and hot gas. Here we use the relative strengths of the λ5780 and λ5797 DIBs in the spectra of stars in the Solar Neighbourhood, globular clusters, and the Magellanic Clouds to map the small scale structure in the warm ISM.

Wide field Imaging of the Hubble Deep Field using MERLIN and e-MERLIN

Author: Nick Wrigley

Jodrell Bank Centre for Astrophysics

Co-Authors:

Session: GAL: Physics of galaxies at high and low redshift (includes Milky Way)

Presentation type: Poster

Summary:

The Hubble Deep Field has been an area of intense study since the initial observations were made by the HST in the mid '90s. Making equivalent wide-field high resolution observations of these distant galaxies at radio wavelengths requires the use of interferometers such as MERLIN, but these introduce issues characteristic of such instruments. Several issues are explored which can be minimised yielding some of the widest high resolution images to date. The results may have important implications for future wide-field imaging using e-MERLIN.

Cross-field transport of non-thermal electrons in thick target coronal loops

Author: Nic Bian

Glasgow University

Co-Authors: E. Kontar, I. Hannah

Session: HEP: High energy particles in the solar system

Presentation type: Poster

Summary:

Turbulence is thought to be involved in various physical processes that occur during solar flares and it is now possible to use RHESSI observations of Hard-X ray emitting electrons to estimate the magnitude of the magnetic field line diffusion in dense coronal loops. Our aim is to discuss the cross-field transport of non-thermal electrons resulting from the presence of broadband magnetic fluctuations in coronal loops. It is shown that a substantial variation in the level of magnetic fluctuations, that can be inferred from the observations, is possible whether the regime of transport is quasi-linear or non-linear.

Effect of self-induced electric field on Langmuir turbulence generated by electron beams in flares

Author: Prof. Valentina Zharkova

University of Bradford

Co-Authors: V.V.Zharkova (University of Bradford, UK) and T.V. Siversky (L'viv University, Ukraine)

Session: HEP: High energy particles in the solar system

Presentation type: Poster

Summary:

The precipitation of an electron beam injected into the solar atmosphere is studied for generation of Langmuir wave turbulence in the presence of collisional and Ohmic losses. It is found that at upper atmospheric levels the self-induced electric field suppresses the generation of Langmuir turbulence to very small regions below injection. With further precipitation into deeper atmosphere the initial single power law distributions of beam electrons are transformed into energy distributions with maxima at lower energies formed by collisional and Ohmic energy depletion. The electrons with lower energies (<20 keV) generate on large spatial scales intense low-hybrid and high-hybrid Langmuir waves with well defined patterns in the corona while higher energy electrons generate moderate low hybrid waves in the chromosphere. The self-induced electric field reduces the level and makes narrower the regions with low-hybrid Langmuir turbulence in the corona and upper chromosphere. High-hybrid Langmuir waves are found to be generated only by a very intense electron beam with the number of patterns being significantly reduced by the self-induced electric field.

Electron Anisotropy in Solar Flares

Author: Ewan Dickson

University of Glasgow

Co-Authors: E.Kontar (University of Glasgow)

Session: HEP: High energy particles in the solar system

Presentation type: Poster

Summary:

The angular variation of high energy electrons during a solar flare is key to understanding the acceleration mechanism. High resolution X-ray spectra observed by RHESSI (Ramaty High Energy Solar Spectroscopic Imager) can be used to estimate this anisotropy. The effect of photospheric albedo, Compton scattering of X-ray photons from the photosphere, should greatly influence the observed spectrum if the X-ray emitting electrons are highly beamed. The observed spectra will thus contain signatures of the anisotropy. The technique of regularised inversion is used to determine the proportion of the electron flux directed downwards towards the photosphere compared to the electron flux directed towards the observer. The RHESSI flare database has been searched and analysis performed on all flares found to have statistically significant counts above 300 keV. In total 9 flares suitable for analysis were found. The anisotropy of these flares both over the entire impulsive phase and for shorter time intervals was measured and the flares have all been found to exhibit angular distributions which is close to isotropic.

Energetic particles at the Chromosphere

Author: Rim Turkmani

Imperial College

Co-Authors: J. C. Brown (University of Glasgow)

Session: HEP: High energy particles in the solar system

Presentation type: Poster

Summary:

With the solar chromosphere revealing itself as a very dynamic and complex region, and with new particle acceleration models that point at the Chromosphere as a major player in energizing accelerated particles (Brown et al 09), a new look at the chromosphere from the particle acceleration point of view is needed. Here, we take a closer look at the solar chromosphere and identify the requirements for energizing particles in this region and the possible mechanisms which are able to provide these requirements. Moreover, we look at the energy budget of solar flares and active regions and see how it changes if the chromosphere is incorporated in this budget as more than just an energy-loss area as it is generally viewed. A new picture emerges that explain many of the paradoxes which stem from the assumption that particles are only accelerated at the corona.

Particle acceleration in 3D self-consistent solutions of the MHD equations

Author: Adam Stanier

University of Manchester

Co-Authors: P.K.Browning (Jodrell Bank Centre for Astrophysics, School of Physics and Astronomy, University of Manchester, Manchester M13 9PL, UK p.browning@manchester.ac.uk); S.Dalla (Jeremiah Horrocks Institute, University of Central Lancashire, Preston, United Kingdom; sdalla@uclan.ac.uk)

Session: HEP: High energy particles in the solar system

Presentation type: Poster

Summary:

Studies of hard X-ray emission in solar flares suggest a large proportion of flare energy is released in the form of non-thermal accelerated particles. It is well accepted that magnetic reconnection plays a significant role in the release of stored magnetic energy in flares, and thus the electric fields associated with reconnection are a prime candidate as a mechanism for accelerating charged particles. Particle acceleration has been studied in some detail within 2D reconnection geometries, using a test particle approach. However, 3D geometries are more relevant to the solar corona, and it is likely that 3D magnetic null points are common in the corona. Some progress has been made using test particle models studying particle acceleration in fields from numerical MHD simulations or analytical models of the outer (ideal) region of 3D reconnecting nulls. Here, we consider particle acceleration using background fields from self-consistent, analytic solutions of the MHD equations (e.g. Craig and Fabling, 1995), which model both the ideal and resistive regions of reconnection. Particle trajectories are analysed in detail, and energy spectra are calculated. The results are compared with the simpler models considered by Dalla and Browning (2005), which incorporated only the ideal region.

Photospheric signatures of eruptive events

Author: Ehsan Pedram

UCL Mullard Space Science Laboratory

Co-Authors: Sarah Matthews (MSSL)

Session: HEP: High energy particles in the solar system

Presentation type: Poster

Summary:

The connections between the site of explosive energy release in the corona and the lower atmosphere remain poorly understood, but hold great potential for understanding eruptive phenomena on the Sun. Herewe focus on the question of the existence of detectable signatures of an equal and opposite downward force during the eruption of a CME. In this context we look for evidence of changes in the photosphere and examine their association with coronal dimmings and so-called EIT waves. We make use of Hinode SOT data to anaylse small scale magnetic field changes at the onset of a flare and the CME, and compare these with coronal observations from SOHO, Hinode and SDO. We interpret these observations in the context of current eruptive flare models.

Coupling of Dungey and Vasyliunas cycle reconnection: Drivers and observable consequences

Author: Chris Arridge

MSSL, University College London

Co-Authors: A.P. Walsh (MSSL UCL)

Session: MAG: Magnetospheres and ionospheres throughout the Universe

Presentation type: Poster

Summary:

System-level models of reconnection cycles in rapidly rotating magnetospheres typically consider the Dungey and Vasyliu Ì„nas cycles in isolation and make specific predictions about the ion composition changes associated with these processes. However, in order to form and release a plasmoid as part of the Dungey cycle, reconnection must occur on closed field lines before any open flux is reconnected. This naturally leads to a coupling of these two cycles. In this presentation we conceptually explore the observable consequences of this coupling in terms of time-dependence in the ion composition of reconnection flows as reconnection proceeds through the closed and then open magnetic flux. We argue that in the absence of any solar wind driving the Vasyliu Ì„nas cycle can in principle proceed in isolation, but the same is not true of the Dungey cycle as long as there is significant mass- loading in a rapidly rotating magnetosphere. We also explore the driving of these cycles using quantitative models of the magnetotail which include the effects of the centrifugal force. The onset of reconnection in the magnetotail depends on a thinning of the current sheet that might arise due to i) stretching of field lines due to the centrifugal force, ii) compression of the plasma sheet by the addition of open flux to the lobes or the passage of a solar wind compression, or iii) a combination of these effects. We consider the stability of the magnetotail to examine whether triggering of tail reconnection due to solar wind compression requires a particular mass content of the magnetotail.

The Magnetosphere of Uranus

Author: Chris Arridge

MSSL, University College London

Co-Authors: N. André (CESR); A. Masters (MSSL UCL); The Uranus Pathfinder Consortium

Session: MAG: Magnetospheres and ionospheres throughout the Universe

Presentation type: Poster

Summary:

The configuration of all the planetary magnetospheres in the solar system is determined by the relative orientations of the planet’s spin axis, its magnetic dipole axis, and the solar wind flow. In the general case, the angle between the magnetic dipole axis and the solar wind flow is a time-dependent quantity and varies on both diurnal and seasonal timescales. Uranus presents a particularly interesting and poorly understood case because this angle not only varies seasonally but because of Uranus’ large obliquity the extent of diurnal oscillation varies with season. At solstice this angle does not vary with time and Uranus’ magnetic dipole simply rotates around the solar wind flow vector. This is a magnetospheric configuration not found anywhere else in the solar system. This unique arrangement may lead to a rapidly reconfiguring system which changes from an open to closed configuration over a uranian day and which may have a closed flow region which does not impede solar-wind driven convection. Uranus thus presents a very different system and represents a challenge for our theories of how magnetospheres work. In this talk we review our understanding of the uranian magnetosphere and discuss future exploration and study of this system.

The UCLan SDO data hub

Author: Silvia Dalla

University of Central Lancashire

Co-Authors: D.S.Brown, S.A.Chapman, M.Marsh, S.Regnier, R.W.Walsh (University of Central Lancashire)

Session: MIS: Solar Missions Forum

Presentation type: Poster

Summary:

A data pipeline for the distribution of SDO data products has been developed throughout a number of countries in the US, Europe and Asia. The UK node within this pipeline is at the University of Central Lancashire (UCLan), where a data center has been established to host a rolling AIA and HMI archive, aimed at supplying SDO data to the large UK solar scientific community. This presentation will describe the hardware and software structures of the archive, with focus on the ways in which scientists can retrieve data. Usage statistics and download speeds for the UCLan hub will also be presented.

A solar wind-magnetosphere coupling function deduced by the NARMAX OLS-ERR algorithm

Author: Richard Boynton

University of Sheffield

Co-Authors: M. A. Balikhin (University of Sheffield); S. A. Billings (University of Sheffield)

Session: MIST: MIST General session

Presentation type: Poster

Summary:

A NARMAX nonlinear system identification technique was used to obtain a solar wind-magnetosphere coupling function. The NARMAX OLS-ERR algorithm is able to determine the causal relationship between input and output for nonlinear systems. The algorithm used solar wind data as the input and the Dst index as the output, which was then able to rank different combinations of the solar wind parameter in order of their predictive capabilities. These obtained coupling functions were compared to those suggested in previous analytical and data based studies. The most appropriate coupling function that the algorithm found was n^(1/2)V^(alpha)B_T sin^6(theta/2), where the power of velocity, alpha, should be in the range 2 - 3.

Combined long term temperature study with EISCAT and Fabry Perot Interferometers

Author: H.C. Iris Yiu

University College London

Co-Authors: Anasuya Aruliah, Eoghan Griffin, Ian McWhirter (UCL)

Session: MIST: MIST General session

Presentation type: Poster

Summary:

There is renewed interest in the monitoring of upper atmospheric temperatures because of the recent extended solar minimum cycle 23/24, as well as the study of the long-term temperature trend in the upper atmosphere due to the increase in green-house gases. Incoherent Scatter radars like EISCAT can be used to provide long-term ion temperatures, which can act as a proxy to the neutral thermospheric temperatures when geomagnetic activity is low. However, this is an indirect measure. The UCL Svalbard Fabry Perot Interferometer (FPI) has been measuring the red line 630.0nm emissions in the high latitude regions for nearly 25 years, and is able to provide direct measurements of the neutral temperature with appropriate calibration. A study of ten years (1999-2009) of FPI neutral temperatures is presented here, with comparisons to the ion temperature measurements from the EISCAT ESR, and semi-empirical model results from MSIS. The potential and importance of a future longer-term combined radar-FPI temperature study is discussed.

Constraining radar interferometer design based on optical aurora images

Author: Sam Tuttle

Southampton University

Co-Authors: Björn Gustavsson (Southampton University), Betty Lanchester (Southampton University)

Session: MIST: MIST General session

Presentation type: Poster

Summary:

The range of spatial frequencies required to undertake interferometric incoherent scatter radar studies of the aurora is presented. The range of frequencies constrains the baseline pattern and hence antenna configuration of the required interferometer. High spatial resolution optical images of the aurora, obtained using the Auroral Structure and Kinetics (ASK) instrument, were used to determine the characteristic spatial frequencies using a Fourier analysis.

Examining the evolution of transient solar wind structures using STEREO/HI

Author: Anthony Williams

University of Leicester

Co-Authors: S.E.Milan (University of Leicester); J.A. Davies (Rutherford Appleton Laboratory)

Session: MIST: MIST General session

Presentation type: Poster

Summary:

The Heliospheric Imagers (HI) on the STEREO spacecraft allow for continuous coverage of transient CMEs in the solar wind as they travel through the inner heliosphere. The HI images produced show light which has been Thomson scattered by free electrons in the solar wind plasma. By taking a cross-section along the ecliptic of these images we examine the relative intensity of the scattered light as a function of radial distance and using multiple such cross-sections we study the evolution of transients with time. In this study we report multiple Earth directed transients and use in-situ data from the ACE spacecraft to gain a further understanding of how different transients evolve during their passage towards the Earth.

Non-Axisymmetry Magnetic Field in the Turbulence Solar Wind at Inertial and Kinetic Scales

Author: Andrew Turner

CFSA, University of Warwick

Co-Authors: S. C. Chapman (CFSA, University of Warwick) G. Gogoberidze (CFSA, University of Warwick) B. Hnat (CFSA, University of Warwick)

Session: MIST: MIST General session

Presentation type: Poster

Summary:

The Solar wind presents a natural example of a high Reynolds, near-collisionless plasma with a well defined power law range for the power spectral density of magnetic field fluctuations observed in-situ, suggestive of an Inertial range of Magnetohydrodynamic turbulence that spans many decades in the time domain. Scaling in magnetic field fluctuations is also observed on temporal scales between the ion and electron gryoperiod, suggesting a kinetic range of turbulence. The kinetic range fluctuations are distinct in character from those of MHD scales, showing non-Gaussian monoscaling behaviour, unlike the MHD inertial range which shows intermittent multiscaling behaviour consistent with fluid turbulence. A recent, unexpected observation is the fluctuations in the magnetic field become progressively less axisymmetric about the local magnetic field as we look on kinetic scales. We perform statistical analysis on Cluster FGM (67Hz) and STAFF (450 Hz) experiment, Stereo FGM (8 Hz) and ACE FGM (0.017 Hz) data in fast solar wind. Power Spectral Density shows a distinct power asymmetry in the two perpendicular directions ordered with respect to the local magnetic field and the solar wind flow direction. We also perform a Minimum Variance Euler Angle Decomposition. The results will be discussed. We acknowledge the ACE, Stereo and Cluster data teams and funding supplied by STFC.

Probing Geospace with VLF radio signals

Author: A. J. Kavanagh

Lancaster University

Co-Authors: M. Denton (Lancaster University); J. Denton (Headlands School and Community Science College); H. Harron (Headlands School and Community Science College)

Session: MIST: MIST General session

Presentation type: Poster

Summary:

Radio waves in the VLF range are guided by the surface of the Earth and the lower edge of the ionosphere. Changes in phase and amplitude of VLF signals are caused by changes in the lower ionosphere (D-layer) along the great-circle path of propagation. A key process that can enhance the D-layer is the precipitation of highly energetic electrons from the Van Allen radiation belts. Thus by monitoring man-made VLF signals from known transmitters one can examine a potentially important radiation belt loss process. The new VLF receiver installed in Bridlington, UK, will monitor unique paths across the radiation belts and form a new part of the AARDDVARK global network of VLF receivers. It is particularly timely given the 2012 launch date for NASA's upcoming Radiation belt Storm Probes mission This experiment is a partnership between Lancaster University scientists and Headlands School in Yorkshire; students from Headlands will have direct access to the data and will undertake projects linking the observations with aspects of the school curriculum. We will present an overview of the system and some initial results.

Simulation of spacecraft surface charging near dusty lunar atmosphere

Author: Farideh Honary

Lancaster University

Co-Authors: A.K. Anuar (Lancaster University), M. Hapgood (CLRC, Lancaster University), J-F. Roussel (Onera)

Session: MIST: MIST General session

Presentation type: Poster

Summary:

A charging simulation by charged dust streaming from lunar surface on spacecraft is presented in this paper. These charged dust is caused by the charging of lunar surface by the solar wind and can be lifted up to 100km when accelerated by the lunar surface's electric field. SPIS software which originally intended to study spacecraft-plasma interaction is extended in order to include dust with varying charge and mass, and Monte Carlo collision algorithm is introduced to simulate the dust-plasma interaction using particle in cell method. The dust charge number depends on the radius and mass, which determine the amount of lift each individual dust experience at certain lunar surface potential. The simulation is set up for near the terminator region of the moon, where streaming dust has been reported, and the spacecraft is modeled as a simple spherical probe made from conducting coating.

Sun et Lumière: Auroral and ionospheric evolution during substorms and ramifications for the Earth’s

Author: Steve Milan

University of Leicester

Co-Authors: S. E. Milan (1), A. Grocott (1), G. Provan (1), J. S. Gosling (1), S. M. Imber (2), and B. Hubert (3) (1) University of Leicester, UK (2) Goddard Space Flight Center, USA (3) University of Liege, Belgium

Session: MIST: MIST General session

Presentation type: Poster

Summary:

We describe the general characteristics of the evolution of the auroral, ionospheric, and magnetotail signatures of magnetospheric substorms. We present results of superposed epoch analyses of 2000 substorms, identified by Frey et al. (2004), of Imager for Magnetopause-to-Aurora Global Exploration (IMAGE) auroral images, Super Dual Auroral Radar Network (SuperDARN) ionospheric flows, and other measures of magnetospheric disturbance. In particular, we examine the effect of the onset latitude on the subsequent evolution of the substorms, the dependence of the onset latitude on the intensity of the ring current, and the solar wind conditions that lead to magnetospheric storm onset. The results are interpreted within the expanding/contracting polar cap paradigm (ECPC), and the ramifications for magnetotail structure and dynamics are discussed.

The variation of F-region radio electron heating with pump power

Author: Andrew Senior

Dept. of Physics, Lancaster University

Co-Authors: M. J. Kosch (Dept. of Physics, Lancaster University)

Session: MIST: MIST General session

Presentation type: Poster

Summary:

The power deposited into the ionospheric electrons by a high-power HF radio wave can be determined by inverting the electron temperature profiles measured by incoherent scatter radar. In this study, an experiment using the EISCAT HF facility and UHF radar are used to investigate how the electron heating varies with the power of the pump radio wave. It is found that the heating is approximately proportional to the pump power, i.e. the efficiency of the heating mechanism is approximately constant with power. The consequences of pump wave absorption in the D-region for heating of the F-region are also investigated.

UCL and Japan FPIs –EISCAT UHF radars tri-static experiment

Author: H.C. Iris Yiu

University College London

Co-Authors: Anasuya Aruliah (UCL), Mike Kosch (Lancaster,STELab), Nozawa Satonori (STELab), Shin-ichiro Oyama (STELab), Kazuo Shiokawa (STELab),Ian McWhirter (UCL), V.S.C.Howells (RAL)

Session: MIST: MIST General session

Presentation type: Poster

Summary:

The results of one of the last tristatic ion-neutral coupling experiments using the EISCAT mainland tristatic radar configuration, with three co-located Fabry-Perot interferometers (FPIs), are presented here. The results show the importance of three-dimensional measurements when studying small-scale structures in the high latitude thermosphere, and the possible applications to the future EISCAT 3D project. The FPIs involved are two UCL FPIs at Kiruna and Sodankylä, as well as a Japanese STELab FPI in Tromsø. Though only bistatic neutral measurements from the FPIs were available due to cloudy sky conditions, we present one of the interesting case studies when an auroral arc appeared under an extremely quiet period in the extended solar minimum in 11th February 2010. Together with the tristatic EISCAT radar results, the FPIs provide a detailed study of the dynamics and energetics of small-scale ion-neutral interactions.

UK Solar System Data Centre - life with NERC and STFC

Author: Matthew Wild

UKSSDC - RAL Space

Co-Authors: S. F. James (UKSSDC - RAL Space) S. J. Pepler (CEDA - RAL Space)

Session: MIST: MIST General session

Presentation type: Poster

Summary:

The UK Solar System Data Centre has now been operating under joint funding by NERC and STFC for a year. As part of our integration within the NERC data centres structure, we need to conduct a data prioritisation exercise to determine the user communities requirements and wishes for the varied historical and current datasets maintained within the UKSSDC. We are therefore conducting a survey of our users requirements and comments on the current UKSSDC service alongside a presentation of the range of data held.

Venus Express: Its contribution to plasma science

Author: Simon Walker

University of Sheffield

Co-Authors: M. A. Balikhin (University of Sheffield); S. A. Pope (University of Sheffield); T. L. Zhang (Austrian Academy of Sciences, Graz)

Session: MIST: MIST General session

Presentation type: Poster

Summary:

The Venus Express spacecraft (VEX) has a very limited plasma package consisting of a particle instrument (ASPERA) and a magnetometer (MAG). VEX is also a magnetically unclean spacecraft. However, in spite of such a limited plasma payload VEX has not only advanced our understanding of Venus-Solar wind interactions but also contribted to fundamental problems of space plasma. Examples of such observations include a new class of collisionless shock that exhibits kinematic relaxation, observations of giant vortices in the magnetosheath that appear to be generated by as a result of the Kelvin-Helmholtz instability at the ionopause, and the probable origin and dynamics of mirror waves. These and other findings of VEX MAG are reviewed.

Amateur collaborations in the field of comet recovery and monitoring using Faulkes Network

Author: Nicholas Howes

Astronomy Now Magazine

Co-Authors: E.C.Baldwin (Astronomy Now)

Session: OUT: Outreach

Presentation type: Poster

Summary:

Comet C/2007 Q3 (Siding Spring) was discovered by Donna Burton in 1986. During the course of its last opposition, amateur astronomer Nick Howes using the 2m Faulkes Telescope in Hawaii along with professional observatories in France and Italy independently and simultaneously detected a significant break up in the comet nucleus. The resultant global media attention and further observations of both this comet and Comet 103P Hartley, where Howes independently calculated the comet rotation speed using rotational gradient processing in commercial software show that professional/amateur collaborations are still important in the field of astronomy, and how, by using amateurs with their unlimited telescope time as the driving force behind projects, outreach and education gains an interface to the world of high end astronomy.

Astronomy Question Of The Day

Author: Dimitri Veras

Institute of Astronomy, University of Cambridge

Co-Authors:

Session: OUT: Outreach

Presentation type: Poster

Summary:

I present an interactive website which engages all people through the use of astronomical trivia, where the primary educational component is the explanation of the answers. The website emphasizes simplicity and ease of use, and aims to allow both young children and seasoned astronomers, as well as all others, to be challenged and have a fun experience. Two questions will be asked each weekday, along with answer explanations for the previous day's questions. Properly accredited photographs are used whenever possible in these explanations. One line of questions is part of a competition which includes "lifelines" and a running tally, and requires user registration. The competition also includes risk assessment and user input. All questions are archived on the site for public use.

Making the most of a poster to attract non-scientific audience

Author: Santiago Vargas Dominguez

Mullard Space Science Laboratory (UCL)s

Co-Authors:

Session: OUT: Outreach

Presentation type: Poster

Summary:

Attracting people without a scientific background to read a poster about science research is not an easy task. It is tricky to strike the optimum balance between aesthetics and the need to convey complex concepts.  Overall such posters should provide an enjoyable experience for the viewer. Apart from the content, some thought should be put in to creating an innovative design including eye-catching images to clarify ideas and highlighting key phrases to make the poster more digestible. Stating the relevance and importance of your research to the reader helps, too. This poster presents cutting-edge research about the magnetic behaviour of the Sun in a style that makes it very attractive to a wide audience by including interactive pop-ups that can be manipulated by the viewer to discover new information.

A Variability Survey of Bright Stars on the Ecliptic Plane with STEREO

Author: Danielle Bewsher

University of Central Lancashire

Co-Authors: K.T. Wraight (1), G.J. White (1,2), D. Bewsher (3), A.J. Norton (2) (1) Department of Physics and Astronomy, The Open University, Milton Keynes, MK7 6AA, UK (2) Space Science and Technology Department, STFC Rutherford Appleton Laboratory, Chilton, Didcot, Oxfordshire, OX11 0QX, UK (3) Jeremiah Horrocks Institute, University of Central Lancashire, Preston, Lancashire, PR1 2HE, UK

Session: PLA: Formation and evolution of planetary systems (including Solar System)

Presentation type: Poster

Summary:

The STEREO mission is able to deliver photometric measurements of stars in the field of view of the satellites' Heliospheric Imagers. The combination of moderately stable photometry, extended continuous viewing periods with moderate cadence and repeated visits is able to provide useful data for stellar variability studies of bright stars (R<12) in the Ecliptic Plane outside the field of view of other surveys. The poster will illustrate this with clear lightcurves of different types of variables.

Anglo-Australian Planet Search

Author: Hugh Jones

University of Hertfordshire

Co-Authors: Jeremy Bailey (University of New South Wales), Paul Butler (Carnegie Institution of Washington), Brad Carter (University of Southern Queensland), James Jenkins (University of Chile), Chris Tinney (University of New South Wales), Rob Wittenmyer (University of New South Wales)

Session: PLA: Formation and evolution of planetary systems (including Solar System)

Presentation type: Poster

Summary:

The Anglo-Australian Planet Search began operation in 1998 January, and is currently surveying 250 stars. It has discovered some 36 exoplanets with m sin i ranging from 5.1 M⊕ to 10 MJup. Latest discoveries and results from our simulations of the underlying exoplanet population will be reported. In particular, the focus will be on the contraints that we can place on the underlying population of Earth-like and Jupiter-like exoplanets in orbit around nearby stars

Bayesian Techniques for Exoplanet Characterisation

Author: Morgan Hollis

UCL

Co-Authors: O.Lahav (UCL); G.Tinetti (UCL)

Session: PLA: Formation and evolution of planetary systems (including Solar System)

Presentation type: Poster

Summary:

Bayesian statistical methods have found many applications in recent years, particularly in cosmology, and are now rapidly being adopted in the area of exoplanets. Here is presented a brief overview of the Bayesian theory, and the Markov Chain Monte Carlo (MCMC) approach to calculating the full posterior distribution in a multi-dimensional parameter space. The theoretical model and the software used to apply the technique, as originally presented by Balan & Lahav (2009), are described, and the results of tests of the software and the initial application to one extrasolar system are shown. It was found that the program performed well in tests using mock data, and was able to accurately recover an input model from simulated data with noise.

Characterising Sodium in the Hot Jupiter HD189733b

Author: Mrs Catherine Huitson

University of Exeter

Co-Authors: D.K.Sing (University of Exeter, UK); A.Vidal-Madjar (CNRS, Institut d'Astrophysique de Paris, France); A.Lecavelier des Etangs (CNRS, Institut d'Astrophysique de Paris, France); J-.M.Desert (Harvard-Smithsonian Center for Astrophysics, USA); G.E.Ballester (University of Arizona, USA)

Session: PLA: Formation and evolution of planetary systems (including Solar System)

Presentation type: Poster

Summary:

The only previous detection of sodium in the atmosphere of HD189733b was ground-based. Space based observations have the advantage of measuring absolute absorption depth, and HST STIS observations were taken for this purpose. Using the G750M grating, the preliminary absorption depth of sodium in the upper atmosphere is (51.1±6.0)x10-5, in good agreement with the previous measurement. The resolution allows us to construct a profile of the line shape and we detect the line core but without any broad wings. We have found that the effects of occulted starspots on the absorption profile and depth are not significant. Previous discovery of a global haze indicates that the sodium we are seeing is high in the atmosphere, above this cover, and we are now fitting the line profile to determine how the temperature changes with altitude. Predictions expect very high temperatures could be seen in the upper atmosphere where stellar UV radiation is unable to escape. This will provide a good comparison to HD209458b, the only other planet that has been profiled in this way, and which has very different atmospheric properties to HD189733b.

Eclipsing binaries and astrophysical false positives in the PLATO fields

Author: Robert Farmer

Open University

Co-Authors: Kolb,U (Open University);Norton, A (Open University)

Session: PLA: Formation and evolution of planetary systems (including Solar System)

Presentation type: Poster

Summary:

We perform binary population synthesis calculations linked to a comprehensive Galactic extinction model to determine the number and type of eclipsing binaries expected in a given field of view with a given magnitude limit. We present selected, preliminary results on fields that are representative of the central, most sensitive region of the proposed PLATO space mission. Our technique has two principal applications: (1) Estimating the number and nature of astrophysical false positive exoplanet transit detections. 2) Constraining the formation history of binary systems by comparing the synthesised signal with a census from an actually observed field.

Investigating planetary statistical distributions

Author: Alex Pettitt

University of Exeter

Co-Authors:

Session: PLA: Formation and evolution of planetary systems (including Solar System)

Presentation type: Poster

Summary:

Since the release of the Kepler planetary candidates the number of possible Earth-like planets has experienced a huge expansion. We look at the recently published data from Kepler and compare the statistical ensemble to the existing planets discover by different radial velocity, with a specific focus on candidates from the HARPS GTO survey and specifically in the range of masses bellow that of Saturn. The overall purpose of which is to obtain a mass-radius relation for planetary companions which can be used as a test for current planetary formation models.

Life & Light: Exotic Forms of Photosynthesis in Binary & Multiple Star Systems

Author: Jack O

University of St Andrews

Co-Authors: J.A.Raven (University of Dundee); C.S.Cockell (Open University); J.S.Greaves (University of St Andrews)

Session: PLA: Formation and evolution of planetary systems (including Solar System)

Presentation type: Poster

Summary:

The potential for hosting photosynthetic life on Earth-like planets within binary/multiple star systems was evaluated by modelling levels of photosynthetically active radiation (PAR). Combinations of M and G stars in: (i) close-binary systems; (ii) wide-binary systems and (iii) three-star systems were explored. A range of stable radiation environments were found to be possible, which allow for the prospect of familiar, but also more exotic forms of phototrophic life, such as infrared photosynthesisers and organisms specialised for specific spectral niches.

Modelling the chemistry of a gravitationally unstable protoplanetary disc

Author: John Ilee

University Of Leeds

Co-Authors: A. Boley (University Of Florida) P. Caselli (University Of Leeds) R. Durisen (Indiana University) T. Hartquist (University Of Leeds) J. Rawlings (University College London)

Session: PLA: Formation and evolution of planetary systems (including Solar System)

Presentation type: Poster

Summary:

Until now, axisymmetric, $\alpha$-disc simulations have been adopted to describe the dynamics used in the construction of chemical models of protoplanetary discs. While this approach is reasonable for many discs, it is not appropriate for young, massive discs in which self-gravity is important. Spiral waves and shocks cause significant temperature and density variations which affect the chemistry. We have used a dynamical model of solar mass star surrounded by a massive (0.39 M$_$), self-gravitating disc to model the chemistry of one of these objects.

Roche Lobes of Hot Jupiter Exoplanets

Author: R. Busuttil

Open University

Co-Authors: C.A.Haswell (Open University)

Session: PLA: Formation and evolution of planetary systems (including Solar System)

Presentation type: Poster

Summary:

The hot Jupiter exoplanets orbit very close to their host stars, and consequently have some similarities to compact binary star systems. For example, the Roche model, which uses the gravitational and centrifugal forces to calculate the equipotentials in the co-rotating frame, is useful in their analysis. In the Roche model, material within the planet’s Roche lobe will be bound to the planet; if the planet’s Roche lobe is over-filled, mass transfer is expected. Several hot Jupiter exoplanets are surrounded by extended exospheres of diffuse neutral gas, detected by the strong absorption it produces in UV resonance lines. In several cases, this gas appears to overfill the planet’s Roche lobe. Several models have been proposed for the origin of the extended exospheric gas: a hydrodynamic “blow-off” caused by the strong irradiation from the host star; tidal disruption of the planet; entrainment of coronal material in the planet’s magnetosphere; charge-exchange reactions with stellar wind particles. We present comparisons of the transit-inferred radii of hot Jupiter planets and their exospheres with their Roche lobes, and discuss what this implies for the mechanisms underlying the exospheric gas.

The shocking UV transit of WASP-12b: A new approach to measuring exoplanetary magnetic fields.

Author: Joe Llama

University of St Andrews

Co-Authors: K. Wood (University of St Andrews), A. A. Vidotto (University of St Andrews), M. M. Jardine (University of St Andrews), Ch. Helling (University of St Andrews)

Session: PLA: Formation and evolution of planetary systems (including Solar System)

Presentation type: Poster

Summary:

We present Monte Carlo radiation transfer simulations of a planet and magnetospheric bow shock transiting a limb-darkened star. We investigate various shock geometries, orientations and densities. Our models accurately reproduce the early ingress observed in WASP-12b, one of the largest transiting exoplanets discovered to date. The results show bow shocks could be a common occurrence amongst hot-Jupiter systems and should provide us with a greater insight into the structure and strength of planetary magnetic fields.

White Dwarfs in the WTS

Author: Paul Steele

Max-Planck-Institut für extraterrestrische Physik

Co-Authors: R. Saglia (MPE), J. Koppenhoefer (MPE), D. Pinfield (University of Hertfordshire)

Session: PLA: Formation and evolution of planetary systems (including Solar System)

Presentation type: Poster

Summary:

We have identified candidate white dwarfs in the WFCAM Transit Survey using Optical to Near-Infrared colours and reduced proper motion. We have analysed the light curves of these stars using standard transit search algorithms and present here the initial results.

Young Stars in N2362: A Spectroscopic and Photometric Study

Author: Lauren M. Weiss

Institute of Astronomy, University of Cambridge

Co-Authors: S. Hodgkin (Institute of Astronomy); M. Irwin (Institute of Astronomy); J. Birkby (Institute of Astronomy); R. Jackson (Keele University); R. Jeffries (Keele University)

Session: PLA: Formation and evolution of planetary systems (including Solar System)

Presentation type: Poster

Summary:

We combine photometric and spectroscopic observations of star cluster NGC 2362 to analyze the statistical properties of stars in this young (~5 Myr) cluster. The candidate cluster members we study are cool (K-type and later) and small (0.1 < M < 1.2). The evolution of young stars in this mass range, specifically the mass-radius relation, is poorly understood due to the dearth of observational constraints. Observations of binary systems in the cluster allow for accurate mass measurements. Our photometric data of 271 candidate cluster members were obtained at the CTIO 4-m Blanco telescope with the Mosaic-II detector. We use multi-epoch spectroscopic data from the ESO VLT telescope, obtained through the GIRAFFE/FLAMES multi-fibre spectrograph on nine nights in December 2007, to study the radial velocities of 116 stars in the cluster field. Measuring their velocities allows us to determine which stars are cluster members and which are outliers (i.e. foreground or background field stars), which improves upon the color-magnitude selection done in previous work. Additionally, we present a preliminary analysis of the eclipsing and spectroscopic binaries in this cluster.

Radio Remote-Sensing Studies of the Inner Heliosphere

Author: Mario M. Bisi

Institute of Mathematics and Physics, Aberystwyth University

Co-Authors: R.A. Fallows (Institute of Mathematics and Physics, Aberystwyth University), A.R. Breen (Institute of Mathematics and Physics, Aberystwyth University), E.A. Jensen (ACS Consulting, Houston), J.M. Clover (Center for Astrophysics and Space Sciences, University of California, San Diego), P.K. Manoharan (Radio Astronomy Centre, National Centre for Radio Astrophysics, Tata Institute of Fundamental Research, Ooty), B.V. Jackson (Center for Astrophysics and Space Sciences, University of California, San Diego), P.P. Hick (Center for Astrophysics and Space Sciences/San Diego Supercomputer Center, University of California, San Diego), J.A. Davies (STFC Rutherford Appleton Laboratory), M.J. Owens (Space Environment Physics Group, Department of Meteorology, University of Reading), and S. Hardwick (Institute of Mathematics and Physics, Aberystwyth University).

Session: RAD: Radio window on the solar system

Presentation type: Poster

Summary:

Radio remote-sensing observations of the inner heliosphere can be undertaken by both the observation of interplanetary scintillation (IPS) of astronomical radio sources and also the observation of Faraday rotation (FR) of spacecraft or astronomical radio sources. The data sets from various IPS-capable systems are used with the University of California, San Diego (UCSD) three-dimensional (3-D) tomographic-reconstruction and visualisation algorithms. We are able to make comparisons with multi-point it in-situ measurements from various deep-space spacecraft using our reconstruction results. This makes possible the study of structure in the inner heliosphere as a whole as well as the ability to isolate individual features or events such as interplanetary coronal mass ejections (ICMEs) or stream interaction regions (SIRs). FR is the rotation that occurs as an electromagnetic wave traverses a birefringent medium such as the solar corona and inner heliosphere. FR is the integrated product of the electron density and the component of the solar magnetic field parallel to the wave vector of the electromagnetic wave. We will present and discuss the most-recent radio remote-sensing observations of the inner heliosphere using the newly-operational LOw Frequency ARray (LOFAR) as well as those results from other radio-capable systems. We will also investigate the global structure of the heliosphere during the current and previous solar minima using radio-based data primarily, and discuss similarities and differences between the two solar cycles where possible.

Saturn’s Radio Emissions and their Relation to Magnetospheric Dynamics

Author: Caitriona Jackman

University College London

Co-Authors: L. Lamy (LESIA, Meudon), P. Zarka (LESIA, Meudon), B.Cecconi (LESIA, Meudon), W.S. Kurth (Univ. of Iowa), M.P. Freeman (BAS), S.W.H. Cowley (Univ. of Leicester), and M.K. Dougherty (Imperial College London)

Session: RAD: Radio window on the solar system

Presentation type: Poster

Summary:

With the arrival of the Cassini spacecraft at Saturn in July 2004, there have been quasi-continuous observations of Saturn Kilometric Radiation (SKR) emissions. We begin by reviewing solar wind data upstream of Saturn and discuss the link between solar wind compressions and dynamics in Saturn's magnetosphere, evidenced by intensifications and occasional phase changes in the SKR emission. We then review the link between magnetotail reconnection and planetary radio emissions. We begin in the well-sampled magnetotail of Earth and then move to Saturn where exploration of the nightside magnetosphere has revealed evidence of plasmoid-like magnetic structures and other phenomena indicative of magnetotail reconnection. In general, there is a good correlation between the timing of reconnection events and enhancements in the SKR emission, coupled with extension of the emission to lower frequencies. We interpret this as growth of the radio source region to higher altitudes along the field lines, stimulated by increased precipitation of energetic electrons into the auroral zones following reconnection. We also comment on the observation that the majority of reconnection events occur at SKR phases where the SKR power would be expected to be rising with time, indicating that reconnection is most likely to occur at a preferred phase. We conclude with a summary of the current knowledge of the link between Saturn's magnetospheric dynamics and SKR emissions, and list a number of open questions for the future.

A Novel New Radar Technique to Study Geomagnetic Storms: Superposed Latitude-Velocity-Time Plots

Author: James Hutchinson

University of Leicester

Co-Authors: D. M. Wright (University of Leicester); S. E. Milan (University of Leicester); A. Grocott (University of Leicester)

Session: SOL: The rise of Solar Cycle 24 and its implications for space weather

Presentation type: Poster

Summary:

Geomagnetic storms cause large global disturbances in the Earth’s magnetosphere, during which large amounts of energy are deposited in the magnetotail and inner magnetosphere, producing an enhanced ring current and energising plasma to relativistic levels by little-known excitation mechanisms. As we approach more active times in solar cycle 24, understanding and predicting the effects of space weather will be crucial in protecting both space and terrestrial based applications such as GPS and national power grids. By exploiting data from the Advanced Composition Explorer (ACE) spacecraft in conjunction with space- and ground-based measurements of geospace over the last solar cycle, a superposed epoch analysis of 143 geomagnetic storms has been completed. Using a superposition method based on average periods of storm phases rather than a simple t0 alignment, it was found that there is a dual trend seen in the main phase duration with storm size, given by maximum negative excursion of SYM-H, contrary to previous studies results. This study makes use of radar backscatter observed by the Super Dual Auroral Radar Network (SuperDARN) and auroral imagery from the IMAGE and POLAR spacecraft missions to better constrain the storm time coupling between the solar wind and magnetosphere and to develop storm phase trends previously identified. We present initial findings of a new radar technique using line of sight, latitude-velocity-time plots analogous to standard RTI plots but using ionospheric convection maps to allow better superposition by removing temporal/spatial problems of moving radars. These, along with cross-cap potential data derived from map potential data, are compared to superposed auroral keograms and the geomagnetic and SW data from our previous study. Initial findings show that the cross cap potential increases during storm main phase and confirm the oval radius - ring current relationship identified by Milan et al., 2009.

Large-Scale Zonal flows during the Solar Minimum and the Rise of Cycle 24

Author: Rachel Howe

Co-Authors: R.W.Komm (National Solar Observatory); F.Hill (National Solar Observatory); J.Christensen-Dalsgaard (Aarhus University); T.P.Larson (Stanford University); J.Schou (Stanford University); M.J.Thompson (High Altitude Observatory/University of Sheffield)

Session: SOL: The rise of Solar Cycle 24 and its implications for space weather

Presentation type: Poster

Summary:

The so-called torsional oscillation is a pattern of migrating zonal flow bands that move from mid-latitudes towards the equator and poles as the magnetic cycle progresses. Helioseismology allows us to probe these flows below the solar surface. The prolonged solar minimum following Cycle 23 was accompanied by a delay of 1.5 to 2 years in the migration of bands of faster rotation towards the equator. During the rising phase of Cycle 24, while the lower-level bands match those seen in the rising phase of Cycle 23, the rotation rate at middle and higher latitudes remains slower than it was at the corresponding phase in earlier cycles, perhaps reflecting the weakness of the polar fields. We will present the latest results based on nearly sixteen years of global helioseismic observations from the Global Oscillation Network Group (GONG) and the Michelson Doppler Imager (MDI) and discuss the implications for the development of Cycle 25.

Two off-phase dynamo waves detected with the PCA analysis of the background and sunspot magnetic fie

Author: Prof. Valentina Zharkova

University of Bradford

Co-Authors: Zharkova V.V., Popova H. and Zharkov S.I.

Session: SOL: The rise of Solar Cycle 24 and its implications for space weather

Presentation type: Poster

Summary:

The variations in latitude and time of the solar background and sunspot magnetic fields in the cycle 21-23 are analyzed with the Principle Component Analysis technique. We identified the two main latitude periodical components of the opposite polarities reflecting two primary waves of the background magnetic field in each hemisphere travelling off-phase. We built the latitudinal distribution for these waves and study the phase relations between the weak background solar magnetic (poloidal) field and strong magnetic field associated with sunspots (toroidal) field. In the attempt to interpret the outcome of PCA analysis, some preliminary model simulations are carried out for the modified Parker’s dynamo theory for few regimes. The outcome is discussed in relation to a weaker solar activity in the cycle 24.

Zonal Modes of CMB Temperature Maps

Author: Jo Short

Cardiff University

Co-Authors: P. Coles (Cardiff University)

Session: STA: Recent developments in astrostatistics

Presentation type: Poster

Summary:

The angular part of the Fourier decomposition in spherical coordinates involve functions known as spherical harmonics. They are frequently used in astronomy for example when looking at the cosmic microwave background (CMB). Spherical harmonic decomposition involves modes labeled by their degree â„“ and order m; individual combinations of these modes generate patchwork patterns over an all-sky map. A special case of these are known zonal modes, i.e when m = 0, and these generate a sky pattern that varies only with latitude. This is of particular interest for the CMB since the zonal modes will align with the galactic plane; any anomalous behavior in them might therefore be an indication of erroneous foreground substraction. In this work we performed a simple statistical analysis of the modes with low â„“ for all sky CMB maps derived via different cleaning procedures from the Wilkinson Microwave Anisotropy Probe (WMAP), and show that the zonal modes provide a useful diagnostic of possible systematics.

Current sheet formation and heating

Author: Ruth Bowness

University of St Andrews

Co-Authors: A. W. Hood (University of St Andrews); C. E. Parnell (University of St Andrews)

Session: TOP: Topology of solar & stellar magnetic fields

Presentation type: Poster

Summary:

Solar photospheric footpoint motions can produce strong, localised currents in the corona. A detailed understanding of the formation process and the resulting heating is important in modelling nanoflares, as a mechanism for heating the solar corona. A 3D MHD simulation is described in which an initially straight magnetic field is sheared in two directions with grid resolutions up to $512^3$. A twisted current layer is formed which reduces in width and increases in maximum current as the grid is refined. This, together with the residual Lorentz forces calculated, suggest that a current sheet is trying to form. Realistic coronal temperatures are obtained.

The disappearance of a prominence

Author: Owen Roberts

Aberystwyth University

Co-Authors: Xing Li(Aberystwyth University)

Session: TOP: Topology of solar & stellar magnetic fields

Presentation type: Poster

Summary:

Using high cadence data from the STEREO B EUVI telescope in the He II 304Ã… line, the disappearing of a prominence above the north west limb is observed between 00:00UT May 9th and 07:00 May 10th 2007. During this prolonged period of activity various motions of material are observed. Under the assumption that that what is observed is cool plasma, the motions are best described as the coronal rain often reported in the literature. This is a reasonable assumption since the 304Ã… bandpass is dominated by the cool (~10,000K) He II line and the contribution of the hotter Si IX is small in comparison. Further support is that the motions are absent in other EUVI hot lines such as 195 Ã…. The motions of the cool plasma appear to initiate from the prominence and fall down to the solar surface along complex magnetic field lines. This includes an instance of material distributed at different heights initially travelling in a parallel manner but eventually falling into the same footpoint. The prominence therefore is a region of concentrated magnetic flux. The prominence becomes thinner and eventually disappears after all the cool plasma falls back to the solar surface along magnetic loops.

The Topology of Flux Emergence and its Observational Consequences

Author: Clare Parnell

University of St Andrews

Co-Authors: Parnell, C.E., Haynes, A.L. and Maclean, R.C.

Session: TOP: Topology of solar & stellar magnetic fields

Presentation type: Poster

Summary:

Flux emergence is a common, wide spread process on the Sun which injects some 10^25 Mx of flux per day into the solar atmosphere. It is known to be a key source of heat for the solar corona and is often associated with flaring and dynamic activity in the solar atmosphere. Using numerical resistive 3D MHD models of flux emergence, we determine the separatrix surfaces and numerous separators found at the interface between the emerging flux tube and overlying coronal field. By comparing these topological structures to the main signatures of 3D reconnection, such as the integrated parallel electric field along fieldlines, we demonstrate that the magnetic skeleton is central to understanding the nature of the reconnection mechanism in flux emergence (Parnell, Maclean and Haynes, Astrophys. J. Lett. 725, 2010). Furthermore, we look at the behaviour of the plasma as a consequences of this reconnection and show how flux emergence leads to the broad heating of many field lines, and possible flaring, which naturally arises from flux emergence.

What's going on in that flux tube?

Author: Anthony Yeates

University of Dundee

Co-Authors: G.Hornig (University of Dundee)

Session: TOP: Topology of solar & stellar magnetic fields

Presentation type: Poster

Summary:

Magnetic loops in solar and stellar coronae are but one example of evolving magnetic flux tubes. Mathematically, a flux tube at a given time snapshot corresponds to a dynamical system, with magnetic field lines corresponding to particle trajectories. This analogy opens up a number of mathematical techniques and ideas that can be exploited to characterise the structure and dynamics of 3D magnetic fields. For example, we can pin down what is meant by complexity of a magnetic field, and quantify how complex a magnetic structure to expect from different photospheric motions. Another exciting area is our recent identification of topological properties that constrain possible evolutions of magnetic loops, including both turbulent and/or resistive dynamics.

A large polar-crown filament eruption observed by SDO/AIA and STEREO-A/EUVI

Author: Caroline Alexander

University of Central Lancashire

Co-Authors: C. E. Alexander, S. Regnier, R. W. Walsh

Session: UKSP: UKSP General session

Presentation type: Poster

Summary:

Using the two points-of-view of SDO/AIA and STEREO-A/EUVI (about 70 degrees apart), we observed a large-scale polar crown filament eruption on 13 June 2010 in the Northern hemisphere. Comparing the plasma at 80000 K and at 0.6 MK, we deduce the structure of the filament/prominence and its evolution. The polar-crown is composed of hot and cool plasma sitting at the bottom of a cavity in upwardly concave magnetic field lines. We also study the different possible initiation processes leading to the eruption by looking at local and global events which can destabilise the filament such as weak filament activity in a nearby active region, a flare and the associated CME wave starting in the Southern hemisphere, existence of a trans-equatorial loop, instability of the filament (kink, torus, mass loading). We discuss the contribution and timing of each initiation process to the filament eruption: the mass loading scenario and the CME wave seem to be the more likely mechanisms.

A Non-Linear Force-Free Field Model for the Solar Magnetic Carpet

Author: Karen Meyer

University of St Andrews

Co-Authors: D. H. Mackay (University of St Andrews); A. A. van Ballegooijen (Harvard-Smithsonian Center for Astrophysics)

Session: UKSP: UKSP General session

Presentation type: Poster

Summary:

Our aim is to construct a 3D non-linear force-free field model for the solar magnetic carpet. Here we present a new 2D model for the photospheric evolution of the magnetic field, that reproduces many observational parameters. The basic evolution of magnetic elements within the model is governed by a supergranular flow profile. In addition, magnetic elements may evolve through the processes of emergence, cancellation, coalescence and fragmentation. The synthetic magnetograms produced by the 2D model will be used as photospheric boundary data to drive the continuous evolution of a 3D non-linear force-free coronal field. We introduce the 3D modeling technique by first applying it to three basic small-scale magnetic interactions: emergence, cancellation and flyby.

Fine structure collisional data for the electron impact excitation of SIII

Author: Claire Hudson

Queen

Co-Authors: C.A. Ramsbottom (QUB); M.P. Scott (QUB)

Session: UKSP: UKSP General session

Presentation type: Poster

Summary:

Electron-ion collision processes are important in understanding the energy balance in various types of plasmas and through the use of theoretical line intensity ratios, electron temperatures, densities, and elemental abundances can be deduced. Several emission lines of S III have been observed in the ultraviolet spectra of the Sun and stellar transition regions (Doschek & Feldman 1987 ApJ 315 L67) and provide important temperature diagnostics. In order to analyse the observational data, accurate excitation collision strength values are needed. However, as reported recently by Rubin et al (2008 MNRAS 387 45) a discrepancy exists in some of the atomic data provided by the IRON Project calculation of Galavis, Mendoza & Zeippen (1995 AASS 111 347) and that of Tayal & Gupta (1999 ApJ 526 544). Therefore we have carried out a new calculation to resolve this discrepancy. Our current work utilises the recently developed parallel RMATRX II suite of codes, which performs the calculation in intermediate coupling and determines collision strengths over an electron energy range of 0-12Ryd. From these, effective collision strengths are generated for electron temperatures in the range log T(K) = 3.0 - 6.0.

Flare velocity shifts using the EVE spectrometer

Author: David Graham

University of Glasgow

Co-Authors: H. S. Hudson (SSL, UC Berkeley) L. Fletcher (University of Glasgow)

Session: UKSP: UKSP General session

Presentation type: Poster

Summary:

The recently launched EVE instrument on the Solar Dynamics Observatory (SDO) has given us access to high cadence uninterrupted flare observations at EUV wavelengths. Using this we present a first look at the impulsive phase of the first X-Class flare in the new solar cycle SOL2011-02-15. At high temperatures we find Fe XXIV 192.028 A to be shifted to high velocities, and with AIA imaging we attempt to observe these flows visually.

Helicity transport in a simulated CME

Author: Bernhard Kliem

UCL, MSSL

Co-Authors: N. Seehafer (Univ. of Potsdam, Germany); S. Rust (Univ. of Potsdam, Germany)

Session: UKSP: UKSP General session

Presentation type: Poster

Summary:

It has been suggested that coronal mass ejections (CMEs) remove the magnetic helicity of active regions from the Sun. Such removal is often regarded to be necessary due to the hemispheric sign preference of the helicity, which inhibits a simple annihilation by reconnection between volumes of opposite chirality. We have monitored the relative magnetic helicity contained in the coronal volume of a simulated flux rope CME, as well as the upward flux of helicity through a horizontal plane in the simulation box. The unstable and erupting flux rope carries away only part of the initial helicity through the open upper boundary of the box; the larger part remains in the volume. We suggest a simple physical explanation for this result.

Independent Signals from the Influence of Internal Magnetic Layers on Frequencies of Solar p-modes

Author: Claire Foullon

University of Warwick

Co-Authors: V.M. Nakariakov (University of Warwick)

Session: UKSP: UKSP General session

Presentation type: Poster

Summary:

The discovery that p-mode frequencies of low degree do not follow changes of solar surface activity during the recent solar minimum offers the possibility of a new diagnostic signature of the responsible pressure perturbation in the wave guiding medium, potentially rich of information regarding the structure of the Sun and the cause of the unusually long solar minimum. Magnetic fields, as well as temperature changes, introduce equilibrium pressure deviations that modify the resonant frequencies of p-mode oscillations. Assuming the perturbation to be caused by a horizontal layer of magnetic field located in a plane-stratified model of the Sun, we compile analytical frequency shifts and process them to allow direct comparison with observations. The effect of magnetism itself on the central p-mode frequencies can be neglected in comparison with the thermal effect of a perturbative layer buried in the solar interior. A parametric study shows that a layer as thin as 2100 km at subsurface depths is able to reproduce reported mean anomalous frequency shifts (not correlated with the surface activity), while a layer of size around 4200 km increasing by a small amount at depths near 0.08 Rsun can explain individual low-degree shifts. It is also possible to obtain the mean shifts via the upward motion through depths near 0.03 Rsun of a rising perturbative layer of thickness around 7000 km. Hence, the anomalous frequency shifts are best explained by thermal effects in the upper regions of the convection zone. The effects of latitudinal distribution are not treated here.

Low-degree Helioseismology from the Solar Dynamics Observatory

Author: Rachel Howe

Co-Authors: A.-M. Broomhall (University of Birmingham); W.J.Chaplin (University of Birmingham); Y.P. Elsworth (University of Birmingham); F. Hill (National Solar Observatory); K. Jain (National Solar Observatory); R.W. Komm (National Solar Observatory)

Session: UKSP: UKSP General session

Presentation type: Poster

Summary:

The Atmospheric Imaging Array (AIA) aboard the Solar Dynamics Observatory (SDO) observes in several ultraviolet and extreme-ultraviolet wavelengths. The 1600 and 1700 Angstrom bands are formed in the upper photosphere and are sensitive to the five-minute oscillations used in helioseismology. We show some preliminary results from the analysis of Sun-as-a-Star time series derived from these data, and compare with results from the Helioseismic and Magnetic Imager, also aboard SDO, and the Birmingham Solar Oscillations network.

Passive scalar transport in sheared turbulence

Author: Dr Andrew Newton

University of Sheffield

Co-Authors: E.kim

Session: UKSP: UKSP General session

Presentation type: Poster

Summary:

The suppression of turbulent transport by large scale shear flows is demonstrated numerically by measuring the turbulent diffusion $D_t$ and scalar amplitude $\langle n'^2\rangle$ of decaying passive scalar fields $n'$ being advected by various turbulent flows. The nature of transport suppression is shown to be crucially depends on the the temporal correlation of the turbulence. Decorrelated prescribed turbulence ($\tau_c=\rightarrow 0$) is found in the strong shear limit to suppress the transport statistics with the shearing rate $\Omega$ as $D_t \propto \Omega^$, $\langle n'^2\rangle\propto\Omega^$ and $\cos\theta\propto\Omega^$. For finite correlated consistantly evolved turbulence ($\tau_c \ge \Omega^$), the scaling of the turbulence statistics with a strong shear is found to be much stronger than those for the decorrelated turbulence, with the scalings of $D_t\propto\Omega^$, $\langle n'^2 \rangle \propto\Omega^$, $\langle u_x'^2 \rangle \propto \Omega^$ and $\langle \omega'^2 \rangle \propto \Omega^$. The results from these different turbulent flows, through utilising a novel renormalisation, are shown to closely match analytical predictions [see E. Kim, Mod. Phys. Lett B , 1 (2004)] for the behaviour of $D_t$ and $\langle n'^2\rangle$. The renormalisation process provides a previously unseen insight into the underlying nature of transport suppression by stable shear flows showing how all the transport statstics are related by the turbulent diffusion.

Proton velocity distribution functions of the solar wind measured by HIA/Cluster

Author: XING LI

Aberystwyth University

Co-Authors:

Session: UKSP: UKSP General session

Presentation type: Poster

Summary:

Proton velocity distribution functions (VDFs) measured by Hot Ion Analyser (HIA) instruments on board the Cluster spacecrafts in the undisturbed solar wind at 1 AU will be presented in this study. The velocity distributions functions carry important information of microscopic wave/particle interactions of the solar wind. The solar wind proton gas is essentially collisionless plasma. The proton velocity distribution functions measured at HIA’s temporal resolution limit (~ 1 minute) are highly non-Maxwellian and non-gyrotropic. However, the relatively low count rates and the poor solid angle resolution of HIA may be also factors that the measured proton VDFs are non-gyrotropic. It is found that the integration of the measured velocity distributions functions over a longer time period (1-2 hours) produce VDFs that are closer to be gyrotropic, reflecting the contributions of plasma waves at various scales during the period and better statistics when more particles being counted. The measured proton VDFs frequently display elongated features along the direction of the background magnetic field. We will discuss possible interpretation of the measurements. These measurements may offer clues to the heating of the solar wind ions.

The Effect of the environment on the P1/P2 period ratio for kink oscillations of coronal loops

Author: Beniamin Orza

University of Sheffield

Co-Authors: Istvan Ballai (University of Sheffield)

Session: UKSP: UKSP General session

Presentation type: Poster

Summary:

The P1/P2 period ratio of transversal loop oscillations is currently used for the diagnostics of longitudinal structuring of coronal loops as its deviation from 2 is intrinsecaly connected to the density scale-height along coronal loops and/or the sub-resolution structure of the magnetic field. Using a straightforward variational method we show that under coronal conditions the effect of the temperature difference between the loop and the enviroment can change considerably the period ratio, this change reaching even 60%. We also show that once dispersive effects are taken account, with oscillation periods shorter than the cut-off period, the domain where the model can be applied is considerably reduced. The same technique is applied not only to coronal structures, but to other oscillating magnetic structures, e.g. prominences.

A Highly Eccentric, Short Period Binary with δ Scuti Pulsations

Author: Kelly Hambleton

UCLan

Co-Authors: D. Kurtz (Jeremiah Horrocks Institute, UCLan); S. Bloemen (Institute for Astronomy, K. U. Leuven); J. Southworth (Astrophysics group, Keele University)

Session: UNS: Unsolved problems of post-main sequence stellar evolution

Presentation type: Poster

Summary:

The Kepler star presented is an eclipsing binary with two stellar components. The primary component is an early A type main sequence star with an approximate temperature of ~8255K, whilst the secondary component is a late F/early A type main sequence star with its temperature comparable to that of the primary. It is currently unknown which component, if not both, is a δ Scuti star. The orbital period of this system is observed to be 2.189 days, with the light curve demonstrating clear ellipsoidal variability and a hump after secondary minimum. This type of variation indicates tidal distortion and extreme interstellar heating. The binary system has been modelled using a the Wilson and Devinney (1971) code (WD), in conjunction with a wrapper made by Southworth et al. (2011), which generates automatic iterations. The frequency spectrum of the pulsation data (the original data with the binary characteristics subtracted) contains both p and g modes. Eight of the g modes are precise multiples of the orbital frequency, to an accuracy greater than 3 σ. This is indicative of the resonant excitation of free Eigen frequencies.

A Semi-Automated Approach to the Abundance Analysis of Ap Stars

Author: Martin Hall

University of Central Lancashire

Co-Authors: H.Bruntt (University of Aarhus); V.Elkin (University of Central Lancashire); D.W.Kurtz (University of Central Lancashire)

Session: UNS: Unsolved problems of post-main sequence stellar evolution

Presentation type: Poster

Summary:

A preliminary analysis of elemental abundances has been performed on a series of high-resolution spectra belonging to approximately 350 Ap stars collected by the FEROS Echelle spectrograph (Fibre-fed, Extended Range, Échelle Spectrograph) located on the 2.2m telescope at La Silla Chile over the period 2007-2010. The technique, calibrated by comparison with standard manual techniques, used a semi-automated set of routines to calculate equivalent widths for a selected number of spectral lines, which were then used to generate abundances using the WIDTH9 program (references). The VWA (v sin i, wavelength shift, abundance analysis) software package was used to determine spectral line sets for analysis, generate spectral plots, and investigate issues of blending and velocity-broadening. Some early results of the survey are presented here.

How Stellar Evolution Uncertainties Affect Planetary Endstates

Author: Dimitri Veras

Institute of Astronomy, Cambridge University

Co-Authors:

Session: UNS: Unsolved problems of post-main sequence stellar evolution

Presentation type: Poster

Summary:

A variety of stellar systems, including those with extreme horizontal branch stars and pulsars, are known to host planets. Changes in the particular evolutionary path of a post-main sequence star can have drastic effects on planetary orbital parameters and ultimately a planet's chance for survival. Here, we analyze the effect of sudden and/or nonlinear stellar mass and radius changes on planetary systems, particularly when a star undergoes a phase transition or exhibits an outburst. We relate these findings to uncertainties in post-main sequence stellar evolution, and quantify the range of planetary endstates allowed by these uncertainties.

R Cassiopeiae: Circumstellar Envelope SiO Maser

Author: Khudhair A. Assaf

JBCA, University of Manchester

Co-Authors: Diamond P. J., Richards A. M. S. and Gray M.

Session: UNS: Unsolved problems of post-main sequence stellar evolution

Presentation type: Poster

Summary:

We present 23 epochs total intensity images of 43GHz, v=1, j=1-0 SiO maser emission toward Mira variable R Cas. Data were recorded at each VLBA antenna at approximate monthly sampling over an optical pulsation phase range of φ= 0.158 to φ = 1.783. These maps show ring-like structure of distribution of the maser features in the shell around the star at a distance almost 1.62 times of the radius of star(R*) from the star's centre. We compare the results with a model produced by Gray et. al. 2009.

Damped large amplitude transverse oscillations in an EUV solar prominence

Author: Jennifer (Harris) Hershaw

University of Warwick

Co-Authors: C.Foullon (University of Warwick); V.M.Nakariakov (University of Warwick, Pulkovo Observatory); E.Verwichte (University of Warwick)

Session: WAV: Waves and transients

Presentation type: Poster

Summary:

We investigate two successive trains of large amplitude transverse oscillations in an arched EUV prominence, observed with SOHO/EIT on the North-East solar limb on 30 July 2005. The oscillatory trains are triggered by large-scale coronal waves, associated with two flares occurring in a remote active region. The oscillations are tracked within rectangular slits parallel to the solar limb at different heights, which move with the apparent height profile of the prominence to account for solar rotation. Time series for the two prominence arch legs are extracted using Gaussian fitting on the 195 Ã… absorption features, and fitted to damped cosine curves to determine the oscillatory parameters. We find agreement between the differing energies of the triggering flares and associated waves, and the velocity amplitudes of the two oscillatory trains. The oscillation period is similar for both trains, indicating a characteristic frequency as predicted by magnetohydrodynamics. The prominence exhibits a global kink mode to a first approximation; however there are also indications that it oscillates as a collection of interacting threads. Combining our results with those of previously analysed kink oscillations in loops, we find an approximately linear dependence of damping time upon period, supporting resonant absorption as the damping mechanism.

Leakage of long-period oscillations from the chromosphere to the corona

Author: Ding Yuan

CFSA, Department of Physics, University of Warwick

Co-Authors: V. M. Nakariakov (1,2) N. Chorley (1) C. Foullon (1) 1. Centre for Fusion, Space and Astrophysics, Department of Physics, University of Warwick, Coventry CV4 7AL, UK 2. Central Astronomical Observatory at Pulkovo of the Russian Academy of Sciences, 196140 St Petersburg, Russia

Session: WAV: Waves and transients

Presentation type: Poster

Summary:

Long-period oscillations in a coronal diffuse structure are detected with the Transition Region And Coronal Explorer (TRACE). The EUV images of the NOAA active region 8253 are available in 171 Ã… and 195 Ã… bandpasses from 30 June to 4 July 1998. As expected, the average intensity variation is connected with the CCD temperature, which varies with the orbital motion of the spacecraft. Hence, oscillations with the orbital period and its higher harmonics appear as artifacts in the light curves. After the exclusion of the orbital effects, we identified several long-period oscillations in the diffuse fan-like structure of the active region. Similar periodicities were detected in the microwave emission from the chromospheric part of that active region, observed with the ground-based Nobeyama Radioheliograph (NoRH) in the 17 GHz channel. It was found that 28 and 72 min oscillations were present in both EUV and microwave emission. From the period values, the detected oscillations could be associated with gravity-driven solar interior modes. The appearance of these oscillations in the coronal part of the active region may be connected with the wave leakage or the evanescence of chromospheric oscillations.

Period persistence of long period oscillations in sunspots

Author: Nicky Chorley

CFSA, Physics Department, University of Warwick

Co-Authors: C. Foullon (University of Warwick), B. Hnat (University of Warwick), V. M. Nakariakov (University of Warwick), and K. Shibasaki (Nobeyama Solar Radio Observatory/NAOJ, Japan)

Session: WAV: Waves and transients

Presentation type: Poster

Summary:

Long period oscillations in the microwave radiation intensity generated over the sunspot of NOAA AR 10330 are studied with the Nobeyama Radioheliograph as the sunspot passes over the solar disk, over the course of 9 days (06-15 April 2003). Periodogram, Fourier and global wavelet analyses reveal the presence of a significant oscillatory component in the range P ~ 50-120 min over the course of the observations. The spectral amplitudes of five significant Fourier components in the range P = 50-150 min are also seen to be stable over the observations, when the data are not affected by changes in magnetic configuration in the region. The ground-based nature of the instrument naturally introduces long data gaps in such long duration observations and the presence of the gaps does not allow any conclusion as to the stability of the phases of the oscillations. As a model to explain the persistence of the dominant long periods, a simple oscillator with a nonlinear driving term is proposed. The spectral difference between distinct peaks within, e.g. the 3 min spectral band, are shown to be able to resonate with the long period one hour oscillations.

Resonantly damped propagating kink waves in longitudinally stratified solar waveguides

Author: Roberto Soler

Centre for Plasma Astrophysics. KU Leuven (Belgium)

Co-Authors: J. Terradas (B); G. Verth (A,C); M. Goossens (A). Inst. A: Centre for Plasma Astrophysics. KU Leuven (Belgium) Inst. B: Solar Physics Group. University of the Balearic Islands (Spain) Inst. C: School of Computing, Engineering and Information Sciences, Northumbria University (UK)

Session: WAV: Waves and transients

Presentation type: Poster

Summary:

It has been shown that resonant absorption is a robust physical mechanism to explain the observed damping of magnetohydrodynamic (MHD) kink waves in the solar atmosphere due to naturally occurring plasma inhomogeneity in the direction transverse to the direction of the magnetic field. Theoretical studies of this damping mechanism were greatly inspired by the first observations of post-flare standing kink modes in coronal loops using the Transition Region And Coronal Explorer (TRACE). More recently, these studies have been extended to explain the attenuation of propagating coronal kink waves observed by the Coronal Multi-Channel Polarimeter (CoMP). In the present study, for the first time we investigate the properties of propagating kink waves in solar waveguides including the effects of both longitudinal and transverse plasma inhomogeneity. Importantly, it is found that the wavelength is only dependent on the longitudinal stratification and the amplitude is simply a product of the two effects. In light of these results the advancement of solar atmospheric magnetoseismology by exploiting high spatial/temporal resolution observations of propagating kink waves in magnetic waveguides to determine the length scales of the plasma inhomogeneity along and transverse to the direction of the magnetic field is discussed.

Slow Magnetoacoustic Waves in Two-Ribbon Flares

Author: Valery Nakariakov

University of Warwick

Co-Authors: I.V. Zimovets (Space Research Institure of RAS, Moscow, Russia)

Session: WAV: Waves and transients

Presentation type: Poster

Summary:

We demonstrate that disturbances observed to propagate along the axis of the arcade in two-ribbon solar flares at the speed of a few tens km/s, well below the Alfv´en and sound speeds, can be interpreted in terms of slow magnetoacoustic waves. The waves can propagate across the magnetic field, parallel to the magnetic neutral line, because of the wave-guiding effect due to the reflection from the footpoints. The perpendicular group speed of the perturbation is found to be a fraction of the sound speed, which is consistent with observations. The highest value of the group speed grows with the increase in the ratio of the sound and Alfv´en speeds. For a broad range of parameters, the highest value of the group speed corresponds to the propagation angle of 25-28 degrees to the magnetic field. This effect can explain the temporal and spatial structure of quasi-periodic pulsations observed in two-ribbon flares.

Small-scale Hα jets in the solar chromosphere

Author: David Kuridze

Astrophysics Research Centre, Queen

Co-Authors: M. Mathioudakis ( Astrophysics Research Centre, School of Mathematics and Physics, Queen’s University Belfast ), D. B. Jess ( Astrophysics Research Centre, School of Mathematics and Physics, Queen’s University, Belfast ), S. Shelyag ( Astrophysics Research Centre, School of Mathematics and Physics, Queen’s University Belfast),

Session: WAV: Waves and transients

Presentation type: Poster

Summary:

We study the horizontal velocities associated with small-scale Hα jets in a decaying active region. Our dataset comprises of simultaneous imaging in Hα, Ca K, G-band, and line-of-sight magnetograms. The observations were obtained with the ROSA imaging system at the Dunn Solar Telescope. The Hα images are highly dynamic, displaying jet velocities as high as 35 km/s. At the photopsheric level, the origin of the jets is associated with Ca K brightenings and G-band bright points. We suggest that the siphon flow model of Doyle et al. (2006) is suitable for interpretation of our observation. The observed Hα jets can be considered as siphon flows in the chromospheric loop, driven by the heating pulse at one of the loop footpoints.

Spatial seismology of a large coronal loop from EUV observations of its transverse oscillations

Author: Erwin Verwichte

University of Warwick

Co-Authors: C.Foullon (University of Warwick); T.Van Doorsselaere (Katholieke Universiteit Leuven, Belgium)

Session: WAV: Waves and transients

Presentation type: Poster

Summary:

We present a study of transverse loop oscillations in a large coronal loop arcade, using observations from TRACE and EIT/SoHO. For the first time we reveal the presence of long-period transverse oscillations with periods between 24 minutes and 3 hr. One loop bundle, 690 Mm long and with an oscillation period of 40 minutes, is analysed in detail. The oscillation quality factor is similar to what has been found earlier for oscillations in much shorter loops. This indicates that the damping mechanism of transverse loop oscillations is independent of loop length or period. The displacement profile along the whole length of the oscillating loop is determined for the first time. By comparing the observed profile with models of the three-dimensional geometry of the equilibrium and perturbed loop, we test the effect of longitudinal structuring (spatial seismology) and find that the observations cannot unambiguously distinguish between loop structuring and non-planarity. Associated intensity variations with a similar periodicity are discussed. Also, we report intensity oscillations at the loop footpoint, which are in anti-phase with respect to the intensity oscillations in the loop body. Lastly, this observation offers the first opportunity to Alfven speed profile in the global corona.

Transverse Coronal Loop Oscillations Seen in Unprecedented Detail by SDO/AIA

Author: Rebecca White

University of Warwick

Co-Authors: E.Verwichte (University of Warwick)

Session: WAV: Waves and transients

Presentation type: Poster

Summary:

We Present an observational study of transverse oscillations of several coronal loops observed in three separate events using data from the Solar Dynamics Observatory (SDO) which provides unprecedented temporal and spatial resolution of the solar corona. We study oscillatory events using the Atmospheric Imaging Assembly (AIA) instrument on board SDO, primarily in the 171Ã… bandpass to obtain information on loop lengths, periods and damping times. Where possible, data from SDO/AIA has been complimented with data from STEREO in order to obtain an estimation of loop inclination angles. Transverse oscillations in solar coronal structures have important applications for coronal seismology where the diagnostic power of the transverse waves can provide information on coronal magnetic and density structuring. Also oscillating loops are often observed to be at or near the site of flares and so can provide information about the physical conditions in the vicinity of these events.

Velocity flows inside NOA AR 10720 derived by temporally evolving ring diagram analysis

Author: Balázs Pintér

Aberystwyth University

Co-Authors: K. Burrows (Aberystwyth University)

Session: WAV: Waves and transients

Presentation type: Poster

Summary:

Between 13th and 16th January 2005, NOA active region 10720 was the site of several large flare events. On 15th January, an X1.2 class flare became seismically active and produced one of the largest flare-induced quakes ever observed by the SOHO spacecraft. The quake rapidly expanded into the surrounding active-region plasma causing a disturbance to the internal velocity fields within the region. Using a temporal scanning technique for helioseismic ring diagram analysis of SOHO/MDI dopplergrams, we have calculated the internal flows of the region and the subsurface factors which might have contributed to the quake event.

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