High resolution observations of white-light emissions from the opacity minimum during an X-class flare

Using high cadence, high resolution near infrared (NIR) observations of the X 10 white-light flare (WLF) on 2003 October 29, we investigated the evolution of the core-halo structure of white-light emission during the two-second period flare peak. We found that size and intensity of the halo remained almost constant in the range of 10 Mm(2). However, the core area was very compact and expanded rapidly from about 1 Mm(2) to 4 Mm(2). At the same time, the total emission of the core increased nearly twenty times. This distinct behavior indicates that different heating mechanisms might be responsible for core and halo emissions. In addition to the temporal analysis, we compared the intensity enhancements of the flare core and halo. The result shows that the halo contrast increased by about 8% compared to the flare-quiet region, which could be explained by a combination of direct-heating and backwarming models. (C) 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim