R. A. Maurya, P. Vemareddy, A. Ambastha
The first X-class flare of the current solar cycle 24 occurred in Active
Region NOAA 11158 during its central meridian passage on 2011 February 15. This
two ribbon white-light flare was well observed by the Helioseismic and Magnetic
Imager (HMI) on board Solar Dynamics Observatory (SDO). During the peak phase
of the flare, we detected magnetic and Doppler velocity transients appearing
near the umbral boundary of the main sunspot. These transients persisted for a
few minutes and showed spatial and temporal correspondence with the flare
kernels. The observed magnetic polarity at the transients' locations underwent
sign reversal, together with large enhancement in Doppler velocities. We
explain this observational phenomena using the HMI spectral data obtained
before, during and after the flare. These changes were reflected in the maps of
the AR in all the Stokes parameters. Association of the transient features with
various signatures of the flare and the cause and effects of their appearance
are also presented on the basis of present theoretical models.
View original:
http://arxiv.org/abs/1106.4166
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