On the origin of a sunquake during the 2014 March 29 X1 flare

Judge, P. G., Kleint, L., Donea, A., Dalda, A. S. and Fletcher, L. (2014) On the origin of a sunquake during the 2014 March 29 X1 flare. Astrophysical Journal, 796(2), p. 85. (doi:10.1088/0004-637X/796/2/85)

Judge, P. G., Kleint, L., Donea, A., Dalda, A. S. and Fletcher, L. (2014) On the origin of a sunquake during the 2014 March 29 X1 flare. Astrophysical Journal, 796(2), p. 85. (doi:10.1088/0004-637X/796/2/85)

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Abstract

Helioseismic data from the HMI instrument have revealed a sunquake associated with the X1 flare SOL2014-03-29T17:48 in active region NOAA 12017. We try to discover if acoustic-like impulses or actions of the Lorentz force caused the sunquake. We analyze spectro-polarimetric data obtained with the Facility Infrared Spectrometer (FIRS) at the Dunn Solar Telescope (DST). Fortuitously the FIRS slit crossed the flare kernel close to the acoustic source, during the impulsive phase. The infrared FIRS data remain unsaturated throughout the flare. Stokes profiles of lines of Si I 1082.7 nm and He I 1083.0 nm are analyzed. At the flare footpoint, the Si I 1082.7 nm core intensity increases by a factor of several, the IR continuum increases by 4 +/- 1%. Remarkably, the Si I core resembles the classical Ca II K line's self-reversed profile. With nLTE radiative models of H, C, Si and Fe these properties set the penetration depth of flare heating to 100 +/- 100 km, i.e. photospheric layers. Estimates of the non-magnetic energy flux are at least a factor of two less than the sunquake energy flux. Milne-Eddington inversions of the Si I line show that the local magnetic energy changes are also too small to drive the acoustic pulse. Our work raises several questions: Have we "missed" the signature of downward energy propagation? Is it intermittent in time and/or non-local? Does the 1-2 s photospheric radiative damping time discount compressive modes?

Item Type:Articles
Keywords:Sun: atmosphere, Sun: chromosphere, Sun: corona, Sun: flares, Sun: magnetic fields
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Fletcher, Professor Lyndsay
Authors: Judge, P. G., Kleint, L., Donea, A., Dalda, A. S., and Fletcher, L.
Subjects:Q Science > QB Astronomy
Q Science > QC Physics
College/School:College of Science and Engineering > School of Physics and Astronomy
Research Group:Astronomy & Astrophysics
Journal Name:Astrophysical Journal
Publisher:American Astronomical Society
ISSN:0004-637X
ISSN (Online):1538-4357
Copyright Holders:Copyright © 2014 The American Astronomical Society
First Published:First published in Astrophysical Journal 796(2):85
Publisher Policy:Reproduced in accordance with the copyright policy of the publisher.
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Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
631581Consolidated grant in solar and astrophysical plasmasLyndsay FletcherScience & Technologies Facilities Council (STFC)ST/L000741/1S&E P&A - PHYSICS & ASTRONOMY