Tomoko Kawate, Ayumi Asai, Kiyoshi Ichimoto. Center-to-limb Variation of Radio Emissions from Thermal-rich and Thermal-poor Solar Flares
Natural Sciences / Astronomy / Solar astronomy
Submitted on: Aug 27, 2012, 22:28:39
Description: A statistical analysis of radio flare events was performed by using the event list of Nobeyama Radioheliograph in 1996-2009. We examined center-to-limb variations of 17GHz and 34GHz flux by dividing the flare events into different groups with respect to the 'thermal plasma richness' (ratio of the peak flux of soft X-ray to non-thermal radio emissions) and the duration of radio bursts. It is found that peak flux of 17 and 34GHz tend to be higher toward the limb for thermal-rich flares with short durations. We propose that the thermal-rich flares, which are supposed to be associated with an efficient precipitation of high energy particles into the chromosphere, have a pitch angle distribution of non-thermal electrons with a higher population along the flare loop.