Physical Properties of White-Light Flares Derived from Their Center-to-LimbDistribution

摘要

We compare the observed center-to-limb distribution of 86 white-light flares(WLFs) with calculated distributions derived from five flare models, each covering different heights, temperatures, and densities in the solar atmosphere. Considering the limited statistics and the possibility of selection effects in reporting WLFs, the following results may be considered tentative: (1) WLFs cannot be modeled solely by high-altitude optically thin sources, by optically thin chromospheric sources, or by photospheric sources located less than 150 km above the tau 50000 = 1 level; (2) middle photospheric sources extending somewhat higher than 150 km provide the best fit to the observed center-to-limb distribution. and (3) middle photospheric sources not exceeding 150 km altitude combined with chromospheric or higher-altitude sources are acceptable. An important feature of this work is that the methods used in the analysis are entirely independent of spectral analysis; yet spectral analysis has provided evidence for both photospheric and chromospheric components in WLFS.... Solar White light flares, Flare distribution in heliographic longitude.