Skip to main content
U.S. Department of Energy
Office of Scientific and Technical Information

X-ray bursts from solar flares behind the limb

Technical Report ·
OSTI ID:4179209
X-ray bursts are identified from the UCSD OSO-7 x-ray experiment data. X-ray spectroheliograms of OSO-5, H alpha activity at the limb, and the emergence and disappearance of sunspot groups at the limb were studied and 17 active centers were found as likely seats of the X-ray bursts beyond the limb. The analysis of 37 X-ray bursts and their physical parameters is presented. Results show that (1) the distributions of maximum temperature, maximum emission measure, and characteristic cooling time of the over-the-limb events do not significantly differ from those of disk events; (2) that radiation is the dominant cooling mechanism for the hot flare plasma; and (3) that the scale height for x-ray emission in the 5-10 keV range is large. Observations show that the fraction of soft x-ray bursts which have a nonthermal component is the same on and off of the disk. Hard x-ray emission over extended regions is indicated. (auth)
Research Organization:
California Inst. of Tech., Pasadena (USA)
NSA Number:
NSA-33-003811
OSTI ID:
4179209
Report Number(s):
N--75-17278; NASA-CR--142132; BBSO--0143
Country of Publication:
United States
Language:
English