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Magneto-Acoustic Energetics Study of the Seismically Active Flare of 15 February 2011 |
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| Authors: | J D Alvarado-Gómez J C Buitrago-Casas J C Martínez-Oliveros C Lindsey H Hudson B Calvo-Mozo |
| Institution: | 1. Observatorio Astron??mico Nacional, Universidad Nacional de Colombia, Bogot??, Colombia 2. Space Sciences Laboratory, University of California, Berkeley, CA, USA 4. NorthWest Research Associates, Boulder, CO, USA 3. Department of Physics & Astronomy, University of Glasgow, Glasgow, Scotland, UK |
| Abstract: | Multi-wavelength studies of energetic solar flares with seismic emissions have revealed interesting common features between them. We studied the first GOES X-class flare of Solar Cycle 24, as detected by the Solar Dynamics Observatory (SDO). For context, seismic activity from this flare (SOL2011-02-15T01:55-X2.2, in NOAA AR 11158) has been reported by Kosovichev (Astrophys. J. Lett., 734, L15, 2011) and Zharkov et?al. (Astrophys. J. Lett., 741, L35, 2011). Based on Dopplergram data from the Helioseismic and Magnetic Imager (HMI), we applied standard methods of local helioseismology in order to identify the seismic sources in this event. RHESSI hard X-ray data are used to check the correlation between the location of the seismic sources and the particle-precipitation sites in during the flare. Using HMI magnetogram data, the temporal profile of fluctuations in the photospheric line-of-sight magnetic field is used to estimate the magnetic-field change in the region where the seismic signal was observed. This leads to an estimate of the work done by the Lorentz-force transient on the photosphere of the source region. In this instance, this is found to be a significant fraction of the acoustic energy in the attendant seismic emission, suggesting that Lorentz forces can contribute significantly to the generation of sunquakes. However, there are regions in which the signature of the Lorentz force is much stronger, but from which no significant acoustic emission emanates. |
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