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NAM2012 - All Presentation Details

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The onset of outflows in NOAA 11117 using SDO

Author: David Shelton

MSSL/UCL

Co-Authors: L.K.Harra (MSSL/UCL) L.M.Green (MSSL/UCL)

Session: SP2: Solar coronal magnetic fields

Presentation type: Talk      00:00  Poster Session B 

Summary:

Coronal outflows have been observed using EUV imaging on TRACE (Winebarger et al. 2001). However, it has only been since the launch of Hinode that direct spectroscopic detection of persistent outflows have been made using the EUV Imaging Spectrometer (EIS, Culhane et al. 2007). These persistent outflows have larger speeds in spectral lines that are formed at T > 1 MK (Del Zanna (2007,2008b), they are found at the edges of active regions and are unchanged over a long period of time. It has been suggested that these persistent outflows could be caused by chromospheric evaporation flow magnetic reconnection (Del Zanna 2008b) and that the outflows could be related to the origin of the slow solar wind (Sakao et al. 2007; Marsch et al. 2008). EIS observations show that these outflows are associated with “open” coronal magnetic field lines (Harra et al. 2008; Doschek et al. 2008). It has recently been shown that emerging flux into an active region can produce new and enhanced outflows (Harra et al. 2010) which have been shown through simulations to be caused by a mixture of compression and magnetic reconnection (Harra et al. 2011). In this work, we choose an example of a region that emerged into quiet Sun and not into a pre-existing active region. We present the results of a study using the Solar Dynamics Observatory (SDO) of the emergence of active region NOAA 11117 which was present on the solar disk between 21st October and 31st October 2010.By using the high spatial resolution and high temporal cadence of SDO, we are able to determine when in the formation of the active region that the onset of these persistent outflows started. The outflows were delayed by 3 and a half days from the region’s first emergence. By comparing the AIA 171Å data with the HMI magnetogram data for this period, we see that the persistent outflows only start to appear after the leading polarity starts to coalesce.

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