DIRECT MAPPING OF SOLAR ACOUSTIC POWER

We investigate the spatial distribution of acoustic power on the Sun a s a function of both horizontal wave-number, k, and temporal frequency , nu. Using time series of full-disk Ca II K line observations, obtain ed at the University of Hawaii's Mees Solar Observatory, we generated a set of six synoptic maps which represent the total acoustic power in tegrated over the three different frequency ranges; (a) 195.3 muHz les s-than-or-equal-to nu less-than-or-equal-to 1790.4 muHz, (b) 1790.4 mu Hz less-than-or-equal-to nu less-than-or-equal-to 5501.3 muHz, and (c) 5501.3 muHz less-than-or-equal-to nu less-than-or-equal-to 8333.3 muH z, for values of k less than or similar to 0.25 Mm-1 and k greater tha n or similar to 0.25 Mm-1. At high temporal frequencies we find ''halo s'' of enhanced acoustic power surrounding active regions. The amount of enhancement is approximately 10% +/- 5% relative to the quiet photo sphere. Both the high- and low-k maps exhibit the phenomenon. Our rath er poor resolution in k does not allow a complete study of the spatial dependence of the halos, but there is some indication that their morp hology may depend weakly on k. The halos extend several tens of Mm bey ond the boundary of the plage as seen in the K line. These appear to b e true solar features, and not an artifact of variable seeing. We also looked for evidence of subphotospheric magnetic structures, such as t he ''fingers'' reported by Braun et al. We find one very faint, diffus e feature apparently connecting an active region in the southern hemis phere with one in the north. We hesitate to say that this is a true si gnature of a subphotospheric structure because of its very low signal level relative to the background. The high-k, p-mode map was examined for any evidence for an acoustic power deficit at the antipodal points of active regions. We estimate that any power deficit at active regio n antipodal points must be no more than approximately 1%, and we there fore conclude that no strong deficit exists at the antipodes of sunspo ts. At low frequencies, both the high- and low-k maps show enhanced po wer at the locations of the active regions. This represents active reg ion evolution.