Sir Bernard Lovell OBE FRS, world renowned radio astronomer and former President of the Royal Astronomical Society, has died aged 98.

Born in 1913 in Oldland Common, Gloucestershire, Sir Bernard studied at the University of Bristol before coming to the University of Manchester to work in the Department of Physics in 1936. During the Second World War, Sir Bernard led the team that developed H2S radar, work for which he was later awarded the OBE.

After the war Sir Bernard began work on cosmic rays using ex-military radar equipment. He brought this equipment to the University of Manchester botany site at Jodrell Bank in Cheshire in late 1945, founding the world-famous Observatory which now exists there.

Jodrell Bank is dominated by the 76-metre Lovell Telescope, conceived by Sir Bernard. He worked with engineer Sir Charles Husband to build the telescope which has become an icon of British science and engineering and a landmark in the Cheshire countryside.

A hugely ambitious project, the telescope was by far the world's largest when it was completed in 1957 and within days tracked the rocket that carried Sputnik 1 into orbit, marking the dawn of the space age. It is still the third largest steerable telescope in the world and a series of upgrades mean it is now more capable than ever, observing phenomena undreamt of when it was first conceived.

The telescope and Observatory continue to play a key role in astronomical research. Jodrell Bank is now home to the e-MERLIN array of seven radio telescopes spread across the UK and is the headquarters for the Square Kilometre Array (SKA), set to become the most sensitive radio telescope ever constructed and due to commence full operations in 2024.

Sir Bernard was President of the Royal Astronomical Society from 1969-1971 and in 1981 his immense contribution to astronomy was recognised with the award of the Society's Gold Medal.

Prof. David Southwood, current President of the Royal Astronomical Society, said: "Sir Bernard was truly one of the giants of British astronomy and space science, an iconic figure who was one of the pioneers of radio astronomy and of the space age. Thanks to his efforts, the UK has been a world leader in this field for more than six decades, a legacy that will continue with our involvement in the Square Kilometre Array."

'Sir Bernard was an iconic figure; a man who helped us to see the universe in an entirely new way and whose work allowed us to make some of the key discoveries of the modern age".

In 2010 scientists discovered four 'monster' sized stars, with the heaviest more than 300 times as massive as our Sun. Despite their incredible luminosity, these exotic objects, located in the giant star cluster R136 in the nearby galaxy the Large Magellanic Cloud; have oddly so far been found nowhere else. Now a group of astronomers at the University of Bonn have a new explanation: the ultramassive stars were created from the merger of lighter stars in tight binary systems. The team present their results in the journal Monthly Notices of the Royal Astronomical Society.

An image of the Wolf-Rayet star R136a1, the most massive star known. Credit: Wikipedia. Click for a larger imageThe Large Magellanic Cloud (LMC), at a distance of 160000 light years, is the third nearest satellite of the Milky Way galaxy we live in and contains around 10 billion stars. The LMC has many star forming regions, with by far the most active being the 1000 light year diameter 'Tarantula Nebula' where the four supermassive stars are found. This cloud of gas and dust is a highly fertile breeding ground of stars in the LMC also known as the "30 Doradus" (30 Dor) complex. Near the centre of 30 Dor is R136, by far the brightest stellar nursery not just in the LMC but in the entire 'Local Group' of more than 50 galaxies (including our own) and the site of the perplexing ultramassive stars.

Until the discovery of these objects in 2010, observations of the Milky Way and other galaxies suggested that the upper limit for stars formed in the present day universe was about 150 times the mass of the Sun. This value represented a universal limit and appeared to apply wherever stars formed.

"Not only the upper mass limit but the whole mass ingredient of any newborn assembly of stars appears identical irrespective of the stellar birthplace", says Prof. Dr Pavel Kroupa of the University of Bonn, a co-author on the new paper. "The star birth process seems to be universal".

The newly discovered four ultrabright ultramassive stars in R136 are quite an exception to this widely accepted limit. Does their discovery mean that the star birth in the 30 Dor region is happening in a very different way from elsewhere in the universe? If so it would challenge the universal nature of the process of star formation, a fundamental premise of modern astronomy.

The Bonn group, also including lead investigator Dr Sambaran Banerjee and team member Seungkyung Oh, modelled the interactions between stars in a R136-like cluster. Their computer simulation assembled the model cluster star by star, so as to resemble the real cluster as closely as possible, creating a cluster of more than 170,000 stars packed closely together. At the outset Seungkyung ensured that the stars were all of a normal mass and were distributed in the way expected.

To compute how even this relatively basic system changes over time, the model had to solve 510,000 equations many times over. The simulation is complicated by the effect of the nuclear reactions and hence energy released by each star and what happens when two stars happen to collide, a frequent event in such a crowded environment.

These highly intensive, star by star calculations are known as 'direct N-body simulations' and are the most reliable and accurate way to model clusters of stars. The Bonn researchers used the N-body integration code "NBODY6", developed primarily by Sverre Aarseth of the Institute of Astronomy in Cambridge and took advantage of the unprecedented hardware acceleration of video-gaming cards installed in otherwise ordinary workstations to fast forward their calculations.

"With all these ingredients, our R136 models are the most difficult and intensive N-body calculations ever made", say Pavel and Seungkyung.

"Once these calculations were done, it quickly became clear that the ultramassive stars are no mystery", adds Sambaran. "They start appearing very early in the life of the cluster. With so many massive stars in tight binary pairs, themselves packed closely together, there are frequent random encounters, some of which result in collisions where two stars coalesce into heavier objects. The resulting stars can then quite easily end up being as ultramassive as those seen in R136.

"Imagine two bulky stars closely circling each other but where the duo gets pulled apart by the gravitational attraction from their neighbouring stars. If their initially circular orbit is stretched enough, then the stars crash into each other as they pass and make a single ultramassive star", Sambaran explains.

"Although extremely complicated physics is involved when two very massive stars collide, we still find it quite convincing that this explains the monster stars seen in the Tarantula", says Banerjee.

"This helps us relax", concludes Kroupa, "Because the collisions mean that the ultramassive stars are a lot easier to explain. The universality of star formation prevails after all."

Dr Sambaran Banerjee
Argelender-Institut für Astronomie (University of Bonn)
Auf dem Hügel 71
D-53121 Bonn, Germany
Tel: +49 (0) 22873 3461
Mob: +49 (0) 151 40519254
This e-mail address is being protected from spambots. You need JavaScript enabled to view it

Prof. Dr Pavel Kroupa
Argelender-Institut für Astronomie (University of Bonn)
Auf dem Hügel 71
D-53121 Bonn, Germany
Tel: +49 (0) 22873 6140
Mob: +49 (0) 177 9566127
Email: This e-mail address is being protected from spambots. You need JavaScript enabled to view it

Dr Robert Massey
Royal Astronomical Society
Mob: +44 (0)794 124 8035
This e-mail address is being protected from spambots. You need JavaScript enabled to view it

http://www.astro.uni-bonn.de/~sambaran/R136pics/R136_zoom.jpg

The "super-cluster" R136 in the Tarantula nebula. From left to right: the Tarantula nebula and the R136 cluster within it. Using a combination of instruments on ESO's Very Large Telescope, astronomers have discovered the most massive stars to date, some weighing at birth more than 300 times the mass of the Sun, or twice as much as the currently accepted limit of 150 solar masses. The most extreme of these stars was found in the cluster R136. Named R136a1, it is found to have a current mass of 265 times that of the Sun. The origin of such monster stars is a challenge for the current understanding of star formation mechanisms. Credit: European Southern Observatory.

http://www.astro.uni-bonn.de/~sambaran/R136pics/R136a1_artist1.jpg

This artist's impression shows the relative sizes of young stars, from the smallest "red dwarfs", weighing in at about 0.1 solar masses, through low mass "yellow dwarfs" such as the Sun, to massive "blue dwarf" stars weighing eight times more than the Sun, as well as the 300 solar mass star named R136a1. Credit: European Southern Observatory.

http://www.astro.uni-bonn.de/~sambaran/R136pics/R136a1_artist2.jpg

An illustration of the Wolf-Rayet star R136a1, the most massive star known. Credit: Wikipedia

The new research was funded by the Deutsche Forschungsgemeinschaft (DFG). It appears in "The emergence of super-canonical stars in R136-type star-burst clusters", S. Banerjee, P. Kroupa, Seungkyung Oh, Monthly Notices of the Royal Astronomical Society, in press. A preprint of this paper can be downloaded from http://arxiv.org/abs/1208.0826

The Royal Astronomical Society (RAS, www.ras.org.uk), founded in 1820, encourages and promotes the study of astronomy, solar-system science, geophysics and closely related branches of science. The RAS organizes scientific meetings, publishes international research and review journals, recognizes outstanding achievements by the award of medals and prizes, maintains an extensive library, supports education through grants and outreach activities and represents UK astronomy nationally and internationally. Its more than 3500 members (Fellows), a third based overseas, include scientific researchers in universities, observatories and laboratories as well as historians of astronomy and others.

Follow the RAS on Twitter via @royalastrosoc

Type Ia supernovae are violent stellar explosions. Observations of their brightness are used to determine distances in the universe and have shown scientists that the cosmos is expanding at an accelerating rate. But there is still too little known about the specifics of the processes by which these supernovae form. New research, led by Stella Kafka of the Carnegie Institution for Science in the United States, identifies a star system, prior to explosion, which will possibly become a type Ia supernova. The work will appear in the journal Monthly Notices of the Royal Astronomical Society.

An optical / infrared / X-ray composite image of the remnant of Tycho's star, a type Ia supernova seen in 1572. Courtesy of Astronomy Picture of the Day. Credit: NASA / CXC / SAO / JPL-Caltech / MPIA / Calar Alto / O. Krause et al. Click for a large version of this imageThe widely accepted theory is that type Ia supernovae are thermonuclear explosions of a white dwarf star that's part of a binary system—two stars that are physically close and orbit around a common centre of mass. The white dwarf has mass gradually donated to it by its companion. When the white dwarf mass eventually reaches 1.4 times that of the sun, it explodes to produce a type Ia supernova. The crucial questions are: What is the nature of the donor star and how does this white dwarf increase its mass. Also, how would that process affect the properties of the explosion?

With these questions in mind, scientists have been searching for candidate systems that could become type Ia supernovae. There are thousands of possibilities in the candidate pool, none of which have yet been observed to produce an explosion. Recent studies, some of which involved scientists at Carnegie observatories, have identified sodium gas associated with type Ia supernovae. This gas might be ejected from the binary's donor star and linger around the system to be detected after the white dwarf explodes. This provides a clue to the progenitor. Even so, Kafka still compared the search to "looking for a needle in a stellar haystack."

Using data from the DuPont telescope of the Las Campanas observatory in Chile, Kafka and her team—Kent Honeycutt of Indiana University and Bob Williams of the Space Telescope Science Institute— looked at these gas signatures and were able to identify a binary star called QU Carinae as a possible supernova progenitor. It contains a white dwarf, which is accumulating mass from a giant star, and sodium has been detected around the system.

This star belongs to a small category of binaries that are very bright and in which the white dwarf accretes material from its companion at very high rates. Sodium should be produced in the atmosphere of the mass-donor giant star, and it can be ejected from the system via a stellar wind. If the white dwarf of this binary explodes into a supernova, the sodium would be detected with the same sort of signature as those found in other type Ia supernovae.

"We are really excited to have identified such a system," Kafka said. "Understanding these systems, the nature of the two stars, the manner in which mass is exchanged, and their long-term evolution will give us a comprehensive picture on how binaries can create one of the most important explosions in the universe."

Space Scoop

A Space Scoop version of this press release is available, written for children aged 8 and above.

Science contact

Stella Kafka
Tel: +1 202 478 8864
This e-mail address is being protected from spambots. You need JavaScript enabled to view it

Natasha T. Metzler
Science Writer
Carnegie Institution for Science
Tel: +1 202 939 1142
This e-mail address is being protected from spambots. You need JavaScript enabled to view it

Robert Massey
Royal Astronomical Society
Mob: +44 (0)794 124 8035
This e-mail address is being protected from spambots. You need JavaScript enabled to view it

A composite X-ray / optical / infrared image of the remnant of Tycho's star, a type Ia supernova seen in 1572, is available at http://apod.nasa.gov/apod/ap090317.html

The new work appears in the paper "QU Carinae: Supernova Ia in the making?" S. Kafka, K. Honeycutt, B. Williams, Monthly Notices of the Royal Astronomical Society, in press. A preprint of the paper can be seen at http://arxiv.org/abs/1206.6798

Space Scoop release (for children)
http://www.unawe.org/kids/unawe1239/

This work was funded, in part, by the NASA Astrobiology Institute.

The Carnegie Institution for Science (carnegiescience.edu) is a private, non-profit organization headquartered in Washington, D.C., with six research departments throughout the U.S. Since its founding in 1902, the Carnegie Institution has been a pioneering force in basic scientific research. Carnegie scientists are leaders in plant biology, developmental biology, astronomy, materials science, global ecology, and Earth and planetary science.

The Royal Astronomical Society (RAS, www.ras.org.uk), founded in 1820, encourages and promotes the study of astronomy, solar-system science, geophysics and closely related branches of science. The RAS organizes scientific meetings, publishes international research and review journals, recognizes outstanding achievements by the award of medals and prizes, maintains an extensive library, supports education through grants and outreach activities and represents UK astronomy nationally and internationally. Its more than 3500 members (Fellows), a third based overseas, include scientific researchers in universities, observatories and laboratories as well as historians of astronomy and others.

Follow the RAS on Twitter via @royalastrosoc

The colour of night-time skyglow may be about to undergo a radical change worldwide, according to scientists of the Freie Universität Berlin and the Leibniz Institute of Freshwater Ecology and Inland Fisheries. They predict that with increasing use of LED street lamps, the colour of the night sky will become bluer. To track this change, the researchers developed a prototype measurement device, and used it to show that the sky currently contains far more red light on cloudy nights compared to clear nights. Their report, entitled "Red is the New Black", is published in the journal Monthly Notices of the Royal Astronomical Society.

Images of the night sky above Glacier National Park in the USA and above Berlin. In cities, clouds scatter artificial light back down towards the ground, drastically increasing the sky brightness. In natural areas, clouds make the sky darker. Credit: Left photo: © Ray Stinson, Glacier National Park, USA; right photo: © Christopher Kyba, Berlin, Germany. Click for a larger image.Christopher Kyba, physicist at the Freie Universität and lead author of the study, explains that innovations in lighting technology will result in changes in the colour of streetlights. "The current worldwide trend of replacing gas discharge lamps with solid state lighting, such as LEDs, will affect the radiance and spectrum of urban skyglow." In order to understand the potential impacts of this change on ecology, it will be essential to monitor the sky over the long term.

The scientists used the new instrument to study how clouds affect sky brightness in urban areas. "For almost all of evolutionary history, clouds made the night sky darker, just like they do in daytime", said Franz Hölker, ecologist at the Leibniz-Institute of Freshwater Ecology and Inland Fisheries, study author, and leader of the project "Verlust der Nacht" (Loss of the Night). In areas with artificial light the effect of clouds is now reversed, and the size of the effect depends on colour. The researchers found that in Berlin the blue portion of skyglow is 7 times more radiant on cloudy nights than on clear, and 18 times more for the red part.

In the visual range used by most animals, the authors say that cloudy skies are now thousands of times more radiant near cities than they were throughout most of history. They expect that the addition of this extra light affects predatory-prey relationships where the predator hunts using vision, for example between owls and mice.

The sky is blue in daytime because the cloud free atmosphere is very good at scattering short wavelength light. The scientists therefore express concern that unless special care is taken in design and implementation, a switch to whiter LED lights could make the sky much brighter on clear nights. They suggest that cities that have decided to change to solid state lighting should purchase lamps that emit no upward light, and use "warm white" lights with as little blue light as possible.

The research was funded by two interdisciplinary projects, MILIEU and "Verlust der Nacht". The "Verlust der Nacht" project, funded by the German Ministry of Education and Research (BMBF), is specifically devoted to quantifying light pollution and investigating its impact on humans and the environment.

Science contacts

Dr Christopher Kyba
Freie Universität Berlin / Leibniz Institut of Freshwater Ecology and Inland Fisheries
Tel: +49 (0)30 / 838-71140
This e-mail address is being protected from spambots. You need JavaScript enabled to view it

PD Dr Franz Hölker
Leibniz Institut of Freshwater Ecology and Inland Fisheries
Tel: +49 (0)30 / 64 181 665
This e-mail address is being protected from spambots. You need JavaScript enabled to view it

Media contact

Dr Robert Massey
Royal Astronomical Society
Mob: +44 (0)794 124 8035
This e-mail address is being protected from spambots. You need JavaScript enabled to view it

Further information

The new work appears in "Red is the new Black: how the colour of urban skyglow varies with cloud cover", C. C. M. Kyba, T. Ruhtz, J. Fischer, F. Hölker, Monthly Notices of the Royal Astronomical Society, in press. The paper can be seen at http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2966.2012.21559.x/abstract and on Christopher Kyba's home page at http://userpage.fu-berlin.de/~kyba/publications/2012_Kyba_red_is_the_new_black.pdf

Freie Universität release
http://www.fu-berlin.de/presse/informationen/fup/2012/fup_12_206/index.html

Interdisciplinary light pollution research project: www.verlustdernacht.de

Images and captions

Images can be downloaded from http://www.fu-berlin.de/presse/informationen/fup/2012/fup_12_206/index.html

Caption: Images of the night sky above Glacier National Park in the USA and above Berlin. In cities, clouds scatter artificial light back down towards the ground, drastically increasing the sky brightness. In natural areas, clouds make the sky darker. Credit: Left photo: © Ray Stinson, Glacier National Park, USA; right photo: © Christopher Kyba, Berlin, Germany

Notes for editors

The Royal Astronomical Society (RAS, www.ras.org.uk), founded in 1820, encourages and promotes the study of astronomy, solar-system science, geophysics and closely related branches of science. The RAS organizes scientific meetings, publishes international research and review journals, recognizes outstanding achievements by the award of medals and prizes, maintains an extensive library, supports education through grants and outreach activities and represents UK astronomy nationally and internationally. Its more than 3500 members (Fellows), a third based overseas, include scientific researchers in universities, observatories and laboratories as well as historians of astronomy and others.

Follow the RAS on Twitter via @royalastrosoc

The RAS invites applications for grants designed to assist the developing world through astronomy. The RAS-OAD Visiting Experts Programme has now issued its first round of grants and invites applications for a second round of awards.

The Visiting Experts Programme is a partnership between the RAS and the IAU Office of Astronomy for Development (OAD) which funds astronomers based in the UK to visit institutions in the developing world.

Funding of up to £1,000 per grant is available to support visits and other activities which advance the aims of the scheme. There is no explicit deadline; applications will be assessed whenever they are received. Full details, including instructions on how to apply, are available from the OAD.

A new model shows how an elusive type of black hole can be formed in the gas surrounding their supermassive counterparts. In research published in the journal Monthly Notices of the Royal Astronomical Society, scientists from the American Museum of Natural History, the City University of New York, the Jet Propulsion Laboratory of the California Institute of Technology, and the Harvard-Smithsonian Center for Astrophysics propose that intermediate-mass black holes - light-swallowing celestial objects with masses ranging from hundreds to many thousands of times the mass of the Sun - can grow in the gas disks around supermassive black holes in the centres of galaxies. The physical mechanism parallels the model astrophysicists use to describe the growth of giant planets in the gas disks surrounding stars.

This simulated image shows the interaction between a massive gas giant planet (comparable in mass to Jupiter) and a surrounding protoplanetary disk of gas and dust. New research predicts that intermediate-mass black holes can create gaps in gas disks around supermassive black holes, analogous to the gaps produced by giant planets in disks around stars. The gap provides a signature that might give scientists the first glimpse of this elusive type of black hole. Credit: Phil Armitage, University of Colorado"We know about small black holes, which tend to be close to us and have masses a few to 10 times that of our Sun, and we know about supermassive black holes, which are found in the centres of galaxies and have a mass that's millions to billions of times the mass of the sun," said co-author Saavik Ford, who is a research associate in the Museum's Department of Astrophysics as well as a professor at the Borough of Manhattan Community College, City University of New York (CUNY) and a faculty member at CUNY's Graduate Center. "But we have no evidence for the middle stage. Intermediate-mass black holes are much harder to find."

The birth of an intermediate black hole starts with the death of a star that forms a stellar or low-mass black hole. In order for this "seed" to grow, it must collide with and consume other dead and living stars. But even though there are many billions of stars in large galaxies, there's an even greater proportion of empty space, making collisions a very rare occurrence.

The researchers' new model suggests that previous searches for middleweight black holes might have been focused on the wrong birthing ground.

"The recent focus had been on star clusters, but objects there move very quickly and there's no gas, which makes the chances of a collision very slim," said Barry McKernan, a research associate in the Museum's Department of Astrophysics who is a professor at CUNY's Borough of Manhattan Community College and a faculty member at CUNY's Graduate Center.

The new mechanism turns attention instead to active galactic nuclei, the piping hot and ultra-bright cores of galaxies that feed supermassive black holes. The gas in this system is the key, causing the stars to slow down and conform to a circularised orbit.

"You can think of the stars as cars travelling on a 10-lane highway," McKernan said. "If there were no gas, the cars would be going at very different speeds and mostly staying in their lanes, making the odds of collision low. When you add gas, it slows the cars to matching speeds but also moves them into other lanes, making the odds of collision and consumption much higher."

The resulting collisions allow a stellar black hole to swallow stars and grow. The black hole's size and gravitational pull increase as its mass expands, escalating its chance of further collisions. This phenomenon, called "runaway growth," can lead to the creation of an intermediate-mass black hole.

As they increase in size, the black holes start altering the gas disk that controls them. The researchers' model shows that black holes of a certain mass can create a gap in the gas disk, a signature that might give scientists the first glimpse of intermediate black holes.

The model describing this growth is a scaled-up version of the mechanism for the formation of gas giant planets like Jupiter and Saturn. Like intermediate black holes, these planets are thought to have grown in gas disks. The planets, though, developed in disks surrounding newly forming stars. Mordecai-Mark Mac Low, chair of the Department of Astrophysics at the Museum, has modelled that case.

"In some regions, we showed that rocky planets could be moved by the gas into common orbits, where they collide to form objects more than ten times the mass of the Earth, massive enough to attract gas and form gas giant planets," Mac Low said. "The creative work described here applies the same principles to the far more massive disks found at the centres of galaxies, to form black holes rather than giant planets."

Other authors on the paper include Museum research associate Wladimir Lyra from the Jet Propulsion Laboratory at the California Institute of Technology and Hagai Perets from the Harvard-Smithsonian Center for Astrophysics.

This work was supported in part by NASA and CUNY.

Kendra Snyder
Department of Communications
American Museum of Natural History
New York City, United States
Tel: +1 212 496 3419
This e-mail address is being protected from spambots. You need JavaScript enabled to view it

An image can be downloaded from http://www.amnh.org/science/papers/intermediateblackhole.php

Caption: This simulated image shows the interaction between a massive gas giant planet (comparable in mass to Jupiter) and a surrounding protoplanetary disk of gas and dust. New research predicts that intermediate-mass black holes can create gaps in gas disks around supermassive black holes, analogous to the gaps produced by giant planets in disks around stars. The gap provides a signature that might give scientists the first glimpse of this elusive type of black hole. Credit: Phil Armitage, University of Colorado

Further information

Research paper: B. McKernan, K.E.S. Ford, W. Lyra, H.B. Perets, "Intermediate mass black holes in AGN disks - I. Production & Growth," Mon. Not. R. Astron. Soc. (2012).

doi: 10.1111/j.1365-2966.2012.21486.x

A preprint of the paper can be downloaded from http://arxiv.org/abs/1206.2309

The American Museum of Natural History (www.amnh.org), founded in 1869, is one of the world's preeminent scientific, educational, and cultural institutions. The Museum encompasses 45 permanent exhibition halls, including the Rose Center for Earth and Space and the Hayden Planetarium, as well as galleries for temporary exhibitions. Five active research divisions and three cross-disciplinary centres support 200 scientists, whose work draws on a world-class permanent collection of more than 32 million specimens and artefacts, including specialized collections for frozen tissue and genomic and astrophysical data, as well as one of the largest natural history libraries in the Western Hemisphere. Through its Richard Gilder Graduate School, it is the first American museum authorized to grant the Ph.D. degree. In 2012, the Museum will begin offering a pilot Master of Arts in Teaching with a specialisation in earth science. Approximately 5 million visitors from around the world came to the Museum last year, and its exhibitions and Space Shows can be seen in venues on five continents. The Museum's website and collection of apps for mobile devices extend its collections, exhibitions, and educational programs to millions more beyond its walls. Visit amnh.org for more information.

Become a fan of the Museum on Facebook via www.facebook.com/naturalhistory, or visit www.twitter.com/AMNH to follow us on Twitter.

The Royal Astronomical Society (RAS, www.ras.org.uk), founded in 1820, encourages and promotes the study of astronomy, solar-system science, geophysics and closely related branches of science. The RAS organizes scientific meetings, publishes international research and review journals, recognizes outstanding achievements by the award of medals and prizes, maintains an extensive library, supports education through grants and outreach activities and represents UK astronomy nationally and internationally. Its more than 3500 members (Fellows), a third based overseas, include scientific researchers in universities, observatories and laboratories as well as historians of astronomy and others.

Follow the RAS on Twitter via @royalastrosoc

Children's radio station Fun Kids Radio has created a new series about an intergalactic school in space. Supported by the RAS, the episodes of 'Deep Space High' are now available as a series of podcasts. The podcasts are particularly aimed at children aged between 7 and 12 years old.

Fun Kids Radio: Deep Space High (including class notes)

Deep Space High podcasts

With large swaths of oceans, rivers that snake for hundreds of miles, and behemoth glaciers near the north and south poles, Earth doesn't seem to have a water shortage. And yet, less than one percent of our planet's mass is locked up in water, and even that may have been delivered by comets and asteroids after Earth's initial formation.

The new model of the early Solar System, where the Earth lies inside the 'snow line'. Click for the full size illustration of this and the old model. Credit: NASA / ESA / A. Feild (STScI)Astronomers have been puzzled by Earth's water deficiency. The standard model explaining how the solar system formed from a protoplanetary disk, a swirling disk of gas and dust surrounding our Sun, billions of years ago suggests that our planet should be a water world. Earth should have formed from icy material in a zone around the Sun where temperatures were cold enough for ices to condense out of the disk. Therefore, Earth should have formed from material rich in water. So why is our planet comparatively dry?

A new analysis of the common accretion-disk model explaining how planets form in a debris disk around our Sun uncovered a possible reason for Earth's comparative dryness. Led by Rebecca Martin and Mario Livio of the Space Telescope Science Institute in Baltimore, Md., the study found that our planet formed from rocky debris in a dry, hotter region, inside of the so-called "snow line." The snow line in our solar system currently lies in the middle of the asteroid belt, a reservoir of rubble between Mars and Jupiter; beyond this point, the Sun's light is too weak to melt the icy debris left over from the protoplanetary disk. Previous accretion-disk models suggested that the snow line was much closer to the Sun 4.5 billion years ago, when Earth formed.

"Unlike the standard accretion-disk model, the snow line in our analysis never migrates inside Earth's orbit," Livio said. "Instead, it remains farther from the Sun than the orbit of Earth, which explains why our Earth is a dry planet. In fact, our model predicts that the other innermost planets, Mercury, Venus, and Mars, are also relatively dry. "

The results have been accepted for publication in the journal Monthly Notices of the Royal Astronomical Society.

In the conventional model, the protoplanetary disk around our Sun is fully ionized (a process where electrons are stripped off of atoms) and is funneling material onto our star, which heats up the disk. The snow line is initially far away from the star, perhaps at least one billion miles. Over time, the disk runs out of material, cools, and draws the snow line inward, past Earth's orbit, before there is sufficient time for Earth to form.

"If the snow line was inside Earth's orbit when our planet formed, then it should have been an icy body," Martin explained. "Planets such as Uranus and Neptune that formed beyond the snow line are composed of tens of percents of water. But Earth doesn't have much water, and that has always been a puzzle."

Martin and Livio's study found a problem with the standard accretion-disk model for the evolution of the snow line. "We said, wait a second, disks around young stars are not fully ionized," Livio said. "They're not standard disks because there just isn't enough heat and radiation to ionize the disk."

"Very hot objects such as white dwarfs and X-ray sources release enough energy to ionize their accretion disks," Martin added. "But young stars don't have enough radiation or enough infalling material to provide the necessary energetic punch to ionize the disks."

So, if the disks aren't ionized, mechanisms that would allow material to flow through the region and fall onto the star are absent. Instead, gas and dust orbit around the star without moving inward, creating a so-called "dead zone" in the disk. The dead zone typically extends from about 0.1 astronomical unit to a few astronomical units beyond the star. (An astronomical unit is the distance between Earth and the Sun, which is roughly 93 million miles.) This zone acts like a plug, preventing matter from migrating towards the star. Material, however, piles up in the dead zone and increases its density, much like people crowding around the entrance to a concert, waiting for the gates to open.

The dense matter begins to heat up by gravitational compression. This process, in turn, heats the area outside the plug, vaporizing the icy material and turning it into dry matter. Earth forms in this hotter region, which extends to around a few astronomical units beyond the Sun, from the dry material. Martin and Livio's altered version of the standard model explains why Earth didn't wind up with an abundance of water.

Martin cautioned that the revised model is not a blueprint for how all disks around young stars behave. "Conditions within the disk will vary from star to star," Livio said, "and chance, as much as anything else, determined the precise end results for our Earth."

Contacts

Donna Weaver / Ray Villard
Space Telescope Science Institute, Baltimore, Md., USA
Tel: +1 410-338-4493 / 410-338-4514
This e-mail address is being protected from spambots. You need JavaScript enabled to view it / This e-mail address is being protected from spambots. You need JavaScript enabled to view it

Mario Livio
Space Telescope Science Institute, Baltimore, Md., USA
Tel: +1 410-338-4439
This e-mail address is being protected from spambots. You need JavaScript enabled to view it

Images relating to this release can be downloaded from http://hubblesite.org/newscenter/archive/releases/2012/28/image/a/

The results are reported in 'On the Evolution of the Snow Line in Protoplanetary Disks', R. Martin and M. Livio. Monthly Notices of the Royal Astronomical Society. A copy of the paper is available from http://hubblesite.org/pubinfo/pdf/2012/28/pdf.pdf

The Royal Astronomical Society (RAS, www.ras.org.uk), founded in 1820, encourages and promotes the study of astronomy, solar-system science, geophysics and closely related branches of science. The RAS organizes scientific meetings, publishes international research and review journals, recognizes outstanding achievements by the award of medals and prizes, maintains an extensive library, supports education through grants and outreach activities and represents UK astronomy nationally and internationally. Its more than 3500 members (Fellows), a third based overseas, include scientific researchers in universities, observatories and laboratories as well as historians of astronomy and others.

Follow the RAS on Twitter via @royalastrosoc

Annual RAS Picnic. Sunday 29th July 2012 - 12:30pm

Celebrating its 23rd year - the picnic has been relocated to the Parish Church of St. Andrew at Kingswood, Surrey, due to the Olympic Equestrian events taking over the public use of Greenwich Park. The vicar is kindly allowing use of the vicarage for Fellows and Guests of the RAS to attend. The full address is Kingswood Vicarage, Woodland Way, Kingswood, Tadworth, Surrey KT20 6NW. There is parking for about 40 cars, but we will have to keep an eye on numbers, so please can you confirm attendance by contacting the organisers – Q Stanley ( This e-mail address is being protected from spambots. You need JavaScript enabled to view it  ) and David Lally ( This e-mail address is being protected from spambots. You need JavaScript enabled to view it  ). 

If you are coming by train, there is a good train service to Kingswood Station which is nearby.

Start time for the picnic will be 12:30pm with the traditional grand opening of a very large bottle of champagne!

We have produced some maps of road and rail links to help you get to Kingswood Vicarage. Please click on the images below to obtain these.

For the first time, dark galaxies — an early phase of galaxy formation, predicted by theory but unobserved until now — have been spotted. These objects are essentially gas-rich galaxies without stars. Using ESO's Very Large Telescope, an international team has detected these elusive objects by observing them glowing as they are illuminated by a quasar. The team report their results in a paper in the journal Monthly Notices of the Royal Astronomical Society.

An image of the region of the sky around the quasar HE0109-3518 (click to enlarge). The quasar is marked with a red circle near the centre of the image, whilst the 12 dark galaxies are marked with blue circles. Credit: ESO, Digitized Sky Survey 2 and S. Cantalupo (UCSC)Dark galaxies are small, gas-rich galaxies in the early Universe that are very inefficient at forming stars. They are predicted by theories of galaxy formation and are thought to be the building blocks of today's bright, star-filled galaxies. Astronomers think that they may have fed large galaxies with much of the gas that later formed into the stars that exist today.

Because they are essentially devoid of stars, these dark galaxies don't emit much light, making them very hard to detect. For years astronomers have been trying to develop new techniques to confirm the existence of these galaxies. Small absorption dips in the spectra of background sources of light have hinted at their existence. However, this new study marks the first time that such objects have been seen directly.

"Our approach to the problem of detecting a dark galaxy was simply to shine a bright light on it." explains Simon Lilly (ETH Zurich, Switzerland), co-author of the paper. "We searched for the fluorescent glow of the gas in dark galaxies when they are illuminated by the ultraviolet light from a nearby and very bright quasar. The light from the quasar makes the dark galaxies light up in a process similar to how white clothes are illuminated by ultraviolet lamps in a night club."

The team took advantage of the large collecting area and sensitivity of the Very Large Telescope (VLT), and a series of very long exposures, to detect the extremely faint fluorescent glow of the dark galaxies. They used the FORS2 instrument to map a region of the sky around the bright quasar HE 0109-3518, looking for the ultraviolet light that is emitted by hydrogen gas when it is subjected to intense radiation. Because of the expansion of the Universe, this light is actually observed as a shade of violet by the time it reaches the VLT.

"After several years of attempts to detect fluorescent emission from dark galaxies, our results demonstrate the potential of our method to discover and study these fascinating and previously invisible objects," says Sebastiano Cantalupo (University of California, Santa Cruz), lead author of the study.

Zoomed images of the 12 dark galaxies, marked with green circles (click to enlarge). Credit: ESO, Digitized Sky Survey 2 and S. Cantalupo (UCSC)The team detected almost 100 gaseous objects which lie within a few million light-years of the quasar. After a careful analysis designed to exclude objects where the emission might be powered by internal star-formation in the galaxies, rather than the light from the quasar, they finally narrowed down their search to 12 objects. These are the most convincing identifications of dark galaxies in the early Universe to date.

The astronomers were also able to determine some of the properties of the dark galaxies. They estimate that the mass of the gas in them is about 1 billion times that of the Sun, typical for gas-rich, low-mass galaxies in the early Universe. They were also able to estimate that the star formation efficiency is suppressed by a factor of more than 100 relative to typical star-forming galaxies found at similar stage in cosmic history.

"Our observations with the VLT have provided evidence for the existence of compact and isolated dark clouds. With this study, we've made a crucial step towards revealing and understanding the obscure early stages of galaxy formation and how galaxies acquired their gas", concludes Sebastiano Cantalupo.

The MUSE integral field spectrograph, which will be commissioned on the VLT in 2013, will be an extremely powerful tool for the study of these objects.

Space Scoop

A Space Scoop version of this press release is available, written for children aged 8 and above.

Images and captions

Images with captions are available on the ESO web page relating to this release.

Contacts

Sebastiano Cantalupo
University of California
Santa Cruz, USA
Tel: +1 831 459 5891
This e-mail address is being protected from spambots. You need JavaScript enabled to view it

Simon J. Lilly
Institute for Astronomy, ETH Zurich
Zurich, Switzerland
Tel: +41 44 633 3828
This e-mail address is being protected from spambots. You need JavaScript enabled to view it

Richard Hook
ESO, La Silla, Paranal, E-ELT & Survey Telescopes Press Officer
Garching bei München, Germany
Tel: +49 89 3200 6655
Mobile: +49 151 1537 3591
This e-mail address is being protected from spambots. You need JavaScript enabled to view it

More information

This research is presented in a paper entitled "Detection of dark galaxies and circum-galactic filaments fluorescently illuminated by a quasar at z=2.4", by Cantalupo et al. which will appear in Monthly Notices of the Royal Astronomical Society.

The team is composed of Sebastiano Cantalupo (University of California, Santa Cruz, USA), Simon J. Lilly (ETH Zurich, Switzerland) and Martin G. Haehnelt (Kavli Institute for Cosmology, Cambridge, United Kingdom).

A copy and a preprint of the research paper are available, as are photos of the VLT.

Notes for editors

• Fluorescence is the emission of light by a substance illuminated by a light source. In most cases, the emitted light has longer wavelength than the source light. For instance, fluorescent lamps transform ultraviolet radiation — invisible to us — into optical light. Fluorescence appears naturally in some compounds, such as rocks or minerals but can be also added intentionally as in detergents that contain fluorescent chemicals to make white clothes appear brighter under normal light.
• Quasars are very bright, distant galaxies that are believed to be powered by supermassive black holes at their centres. Their brightness makes them powerful beacons that can help to illuminate the surrounding area, probing the era when the first stars and galaxies were forming out of primordial gas.
• This emission from hydrogen is known as Lyman-alpha radiation, and is produced when electrons in hydrogen atoms drop from the second-lowest to the lowest energy level. It is a type of ultraviolet light. Because the Universe is expanding, the wavelength of light from objects gets stretched as it passes through space. The further light has to travel, the more its wavelength is stretched. As red is the longest wavelength visible to our eyes, this process is literally a shift in wavelength towards the red end of the spectrum — hence the name 'redshift'. The quasar HE 0109-3518 is located at a redshift of z = 2.4, and the ultraviolet light from the dark galaxies is shifted into the visible spectrum. A narrow-band filter was specially designed to isolate the specific wavelength of light that the fluorescent emission is redshifted to. The filter was centred at around 414.5 nanometres in order to capture Lyman-alpha emission redshifted by z=2.4 (this corresponds to a shade of violet) and has a bandpass of only 4 nanometres.
• The star formation efficiency is the mass of newly formed stars over the mass of gas available to form stars. They found these objects would need more than 100 billion years to convert their gas into stars. This result is in accordance with recent theoretical studies that have suggested that gas-rich low-mass haloes at high redshift may have very low star formation efficiency as a consequence of lower metal content.
• The year 2012 marks the 50th anniversary of the founding of the European Southern Observatory (ESO). ESO is the foremost intergovernmental astronomy organisation in Europe and the world's most productive astronomical observatory. It is supported by 15 countries: Austria, Belgium, Brazil, the Czech Republic, Denmark, France, Finland, Germany, Italy, the Netherlands, Portugal, Spain, Sweden, Switzerland and the United Kingdom. ESO carries out an ambitious programme focused on the design, construction and operation of powerful ground-based observing facilities enabling astronomers to make important scientific discoveries. ESO also plays a leading role in promoting and organising cooperation in astronomical research. ESO operates three unique world-class observing sites in Chile: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope, the world's most advanced visible-light astronomical observatory and two survey telescopes. VISTA works in the infrared and is the world's largest survey telescope and the VLT Survey Telescope is the largest telescope designed to exclusively survey the skies in visible light. ESO is the European partner of a revolutionary astronomical telescope ALMA, the largest astronomical project in existence. ESO is currently planning a 40-metre-class European Extremely Large optical/near-infrared Telescope, the E-ELT, which will become "the world's biggest eye on the sky".
• The Royal Astronomical Society (RAS, www.ras.org.uk), founded in 1820, encourages and promotes the study of astronomy, solar-system science, geophysics and closely related branches of science. The RAS organizes scientific meetings, publishes international research and review journals, recognizes outstanding achievements by the award of medals and prizes, maintains an extensive library, supports education through grants and outreach activities and represents UK astronomy nationally and internationally. Its more than 3500 members (Fellows), a third based overseas, include scientific researchers in universities, observatories and laboratories as well as historians of astronomy and others.
• Follow the RAS on Twitter via @RoyalAstroSoc