Spectroscopic Signatures Related to a Sunquake |
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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
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Publication Status: ApJ (accepted)
Last Modified: 2015-08-31 09:41
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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 |
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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
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Publication Status: ApJ (submitted)
Last Modified: 2010-05-28 03:01
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