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The microwave and H-alpha sources of the 1992 January 13 flareWe compare X-ray, microwave and H-alpha observations for the 1992 January 13 limb flare. The soft and hard X-ray images of the flare have been studied thoroughly by Masuda et al. (1994) with Yohkoh SXT and HXT images. We find that during the hard X-ray emission peak there is no H-alpha brightening on the disk nor at the limb, so the main ribbons of this flare must be beyond the limb. The microwave source maintains a fixed distance about 10 arcsecs from the optical limb in the frequency range 2.8-14.0 GHz. We interpret this limit in source position as due to the presence of a microwave limb that extends higher than the white-light limb -- to a height of 7300 +/- 1500 km. We believe that the high-frequency microwave emissions are occulted by this extended limb, while the soft and hard X-ray emissions are able to pass through largely unaffected. We also believe, however, that the hard X-ray footpoints are also partially occulted by the photospheric limb, despite the appearance of 'footpoint sources' in HXT data shown by Masuda et al. The smooth X-ray and microwave time profiles, microwave-rich emission relative to hard X-rays, and progressive hard X-ray spectral hardening through the flare peak are all characteristics that we interpret as being a direct result of the occultation of footpoint emission.
Document ID
19950054425
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Wang, H. (California Institute of Technology, Pasadena, CA United States)
Gary, D. E. (California Institute of Technology, Pasadena, CA United States)
Zirin, H. (California Institute of Technology, Pasadena, CA United States)
Kosugi, T. (National Astronomical Observatory of Japan Mitaka, Japan)
Schwartz, R. A. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Linford, G. (Lockheed Palo Alto Research Laboratory, Palo Alto, CA United States)
Date Acquired
August 16, 2013
Publication Date
May 10, 1995
Publication Information
Publication: Astrophysical Journal, Part 2 - Letters
Volume: 444
Issue: 2
ISSN: 0004-637X
Subject Category
SOLAR PHYSICS
Funding Number(s)
CONTRACT_GRANT: NSF ATM-93-11416
CONTRACT_GRANT: NAGW-3005
CONTRACT_GRANT: NSF AST-93-14929
CONTRACT_GRANT: NAG5-2090
CONTRACT_GRANT: NSF ATM-91-22023
CONTRACT_GRANT: NAGW-1972
Distribution Limits
Public
Copyright
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