Seismic Emission From Solar Flares

Local helioseismic diagnostics applied to helioseismic observations from the Michelson Doppler Imager (MDI) on the Solar Heliospheric Observatory (SOHO) have shown the clear signature of seismic emission from three flares during the advent of SOHO. All three of these flares showed the signatures of γ-ray emission indicating the involvement of accelerated protons. Two of the acoustically active flares were recent, October 28 and 29 of 2003, and were observed by RHESSI. In both of these instances, the sources of the acoustic emission acoustic source, determined by computational seismic holography, coincided closely with compact γ -ray signatures of protons. Elementary considerations ofenergy and momentum transfer appear to make chromospheric and photospheric heating by protons favorable for seismic emission from flares. If this is actually the case, proton diagnostics of flares from RHESSI would be useful for identifying acoustically active flares for the Helioseismic Magnetic Imager (HMI) on the Solar Dynamics Observatory (SDO), and possibly for the SOHO/MDI. Given a clear understanding of the effects of flares on Doppler signatures in active regions, acoustic emission from flares can give us a powerful control utility for seismic diagnostics of active regions subphotospheres. This research has benefitted greatly from the keen insights of Valentina Zharkova, Gerald Share, Hugh Hudson, and Sam Krucker. It has been supported by grants from the Living with a Star and Supporting Research and Technology programs of the National Aeronautics and Space Administration and the Stellar Astronomy and Astrophysics branch of the National Science Foundation.