Friday, July 5, 2013

1307.1329 (Alina Donea et al.)

Enhanced sources of acoustic power surrounding AR11429    [PDF]

Alina Donea, Christopher Hanson
Multi-frequency power maps of the local acoustic oscillations show acoustic enhancements (\acoustic-power halos") at high frequencies surrounding large active region. Computational seismic holography reveals a high-frequency \acoustic-emission halo", or \seismic glory" surrounding large active regions. In this study, we have applied computational seismic holography to map the seismic seismic source density surrounding AR 11429. Studies of HMI/SDO Doppler data, shows that the "acoustic halos" and the "seismic glories" are prominent at high frequencies 5-8 mHz. We investigate morphological properties of acoustic-power and acoustic emission halos around an active region to see if they are spatially correlated. Details about the local magnetic ?field from vectormagnetograms of AR 11429 are included. We identify a 15" region of seismic de?ficit power (dark moat) shielding the white-light boundary of the active region. The size of the seismic moat is related to region of intermediate magnetic ?field strength. The acoustic moat is circled by the halo of enhanced seismic amplitude as well as enhanced seismic emission. Overall, the results suggest that features are related. However, if we narrow the frequency band to 5.5-6.5 mHz, we fi?nd that the seismic source density dominates over the local acoustic power, suggesting the existence of sources that emit more energy downward into the solar interior than upward toward the solar surface.
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