qs060.hara09 Posted: 05-Sep-93 Updated: 25-Mar-94 Events specified: N/A
H.Hara
MOTIVATION: I feel that the intensity distribution of simple active regions is
different from that of complicated active regions. And the intensity
distribution of active regions seems to be different from that of
quiet regions. I would like to make it clear using the new sxl files.
It will give the definition of regions observed by SXT.
Update 25-Mar-94
This work has been already finished. Here is an abstract for Kofu symposium.
\section*{Abstract} We report initial analysis of image brightness distributions that concisely represent the spatial structure of the solar X-ray corona. This research makes use of histograms of pixel brightnesses obtained from whole-Sun images from the soft X-ray telescope (SXT) aboard {\it Yohkoh}. We discover that the soft X-ray intensity histogram essentially consists of a power-law distribution in bright regions and another one in less bright regions. Active regions show a power-law intensity distribution, whereas quiet regions have non-power law distribution. The comparison of the histograms in the active and less active phases shows that the integrated soft X-ray variability is related to a variation of the total area and the appearance/disappearance of bright component of active regions. The overall shapes of the X-ray histograms are similar to those of histograms of the photospheric magnetic fields given by Schrijver and Harvey (1989), implying that a coronal brightness distribution is related to a magnetic field distribution on the photosphere.