Seismology of Flaring and Dormant Active Regions

Abstract

We study photospheric and sub-photospheric properties of active and quiet regions observed during 11-17 February 2011 including the first X-class flare X2.2 of the solar cycle 24 which occurred in the active region NOAA 11158 on 15 February 2011. The p-mode parameters and sub-photospheric flows are computed from the ring-diagrams and inversions. We found larger frequency shifts in active regions than quiet regions. The active region NOAA 11158 shows stronger twisted sub-photospheric flows than dormant active regions. The kinetic helicity density of sub-photospheric flows of the active region NOAA 11158 shows different structure on the flare day than the pre- and post flare days.