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Spectroscopic Signatures Related to a Sunquake  

Sarah Matthews   Submitted: 2015-08-31 05:26

The presence of flare related acoustic emission (sunquakes) in some flares, and only in specific locations within the flaring environment, represents a severe challenge to our current understanding of flare energy transport processes. In an attempt to contribute to understanding the origins of sunquakes we present a comparison of new spectral observations from Hinode's EUV imaging Spectrometer (EIS) and the Interface Region Imaging Spectrograph (IRIS) of the chromosphere, transition region and corona above a sunquake, and compare them to the spectra observed in a part of the flaring region with no acoustic signature. Evidence for the sunquake is determined using both time-distance and acoustic holography methods, and we find that, unlike many previous sunquake detections, the signal is rather dispersed, but that the time-distance and 6 and 7 mHz sources converge at the same spatial location. We also see some evidence for different evolution at different frequencies, with an earlier peak at 7 mHz than at 6 mHz. Using EIS and IRIS spectroscopic measurements we find that in this location at the time of the 7 mHz peak the spectral emission is significantly more intense, shows larger velocity shifts and substantially broader profiles than in the location with no sunquake, and that there is a good correlation between blue-shifted, hot coronal, hard X-ray (HXR) and red-shifted chromospheric emission, consistent with the idea of a strong downward motion driven by rapid heating by non-thermal electrons and the formation of chromospheric shocks. Exploiting the diagnostic potential of the Mg II triplet lines, we also find evidence for a single, large temperature increase deep in the atmosphere, consistent with this scenario. The time of the 6 mHz and time-distance peak signal coincides with a secondary peak in the energy release process, but in this case we find no evidence of HXR emission in the quake location, but very broad spectral lines, strongly shifted to the red, indicating the possible presence of a significant flux of downward propagating Alfvén waves.

Authors: Sarah A. Matthews, Louise K. harra, Sergei Zharkov & Lucie M. Green
Projects: GOES X-rays ,Hinode/EIS,IRIS,RHESSI,SDO-AIA,SDO-HMI

Publication Status: ApJ (accepted)
Last Modified: 2015-08-31 09:41
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Anatomy of a solar flare: measurements of the December 14, 2006 X-class flare with GONG, Hinode and RHESSI  

Sarah Matthews   Submitted: 2011-07-12 09:48

This abstract was corrupted following database problems and is being recovered. It will be restored as quickly as possible. Any questions, please send them to Alisdair. Sorry for any incovenience.


Authors: Sarah Matthews, Sergei Zharkov & Valentina Zharkova
Projects: Hinode/SOT,TRACE,RHESSI,GONG

Publication Status: ApJ, In press
Last Modified: 2011-07-12 11:14
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Anatomy of a solar flare: Part I. The solar quake measurements of the December 14, 2006 X-class flare with GONG, Hinode and RHE  

Sarah Matthews   Submitted: 2010-05-28 01:23

Some of the most challenging observations to explain in the context of existing flare models are those related to the lower atmosphere and below the solar surface. Such observations, including changes in the photospheric magnetic field and seismic emission, indicate the poorly understood connections between energy release in the corona and its impact in the photosphere and the solar interior. Using data from Hinode, TRACE, RHESSI and GONG we study the temporal and spatial evolution of the 14 December 2006 X-class flare in the chromosphere, photosphere and the solar interior. We report for the first time the detection of a solar quake using time-distance methods applied to GONG data. We then investigate the connections between the emission at various atmospheric depths, with an emphasis on determining the origin of the acoustic responses observed with the GONG data. We report the horizontal displacements observed in the photosphere linked to the timing and locations of the solar quakes associated with this flare, their vertical and horizontal displacement velocities at different atmospheric depths and their implications for models developed for the interpretation of these observations reported in Part II.

Authors: Sarah Matthews, Sergei Zharkov, Valentina Zharkova
Projects: Hinode/SOT

Publication Status: ApJ (submitted)
Last Modified: 2010-05-28 03:01
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A catalogue of white-light flares observed by Yohkoh  

Sarah Matthews   Submitted: 2003-08-08 09:49

The aspect camera of the Soft X-ray Telescope (SXT) on Yohkoh provided the first systematic survey of white-light flares from an observatory in space. The observations were made in the Fraunhofer g-band at a pixel size of 2.46 arc sec and a typical sample interval on the order of ten seconds.A total of 28 flares with clear white-light signatures were detected, corresponding to GOES events down to the C7.8 level in one case.Above the X-class threshold, all 5 events observed by SXT were observed in white light, and the maximum average contrast observed was 30% relative to the pre-flare continuum brightness of the flare location. We have made comprehensive comparisons of Yohkoh soft X-ray and hard X-ray data for this list of flares. In addition we compare the properties of the WLF sample to a sample of 31 flares that showed no white-light emission. These comparisons show that while white-light continuum emission has a strong association with hard X-ray emission it is also strongly related to coronal overpressure, as determined from the soft X-ray spectrum, indicating a component with a thermal, rather than non-thermal origin.

Authors: Sarah Matthews, Lidia van Driel-Gesztelyi, Hugh Hudson & Nariaki Nitta
Projects: Yohkoh-HXT,Yohkoh-SXT

Publication Status: A&A (in press)
Last Modified: 2003-08-08 09:49
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Abstracts by Author
Spectroscopic Signatures Related to a Sunquake
Anatomy of a solar flare: measurements of the December 14, 2006 X-class flare with GONG, Hinode and RHESSI
Anatomy of a solar flare: Part I. The solar quake measurements of the December 14, 2006 X-class flare with GONG, Hinode and RHE
A catalogue of white-light flares observed by Yohkoh

Related Pages
MSU Solar Physics.
Max Millennium Science Mail Archive.
Max Millennium Message of the Day Mail Archive.
Max Millennium Flare Catalog

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