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Simultaneous SMM flat crystal spectrometer and Very Large Array observations of solar active regionsHigh-resolution images of the quiescent emission from two solar active regions at 20 cm (VLA) and soft X-ray (SMM FCS) wavelengths are compared. There are regions where the X-ray coronal loops have been completely imaged at 20 cm wavelength. In other regions, the X-ray radiation was detected without detectable 20 cm radiation, and vice versa. The X-ray data were used to infer average electron temperatures of about 3-million K and average electron densities of about 2.5 x 10 to the 9th/cu cm for the X-ray emitting plasma in the two active regions. The thermal bremsstrahlung of the X-ray emitting plasma is optically thin at 20 cm wavelength. The 20 cm brightness temperatures were always less than T(e), which is consistent with optically thin bremsstrahlung. The low T(B) can be explained if a higher, cooler plasma covers the hotter X-ray emitting plasma. Thermal gyroresonance radiation must account for the intense 20 cm radiation near and above sunspots where no X-ray radiation is detected.
Document ID
19880031893
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Lang, Kenneth R. (Tufts Univ. Medford, MA, United States)
Willson, Robert F. (Tufts University Medford, MA, United States)
Smith, Kermit L. (Tufts Univ. Medford, MA, United States)
Strong, Keith T. (Lockheed Research Laboratories Palo Alto, CA, United States)
Date Acquired
August 13, 2013
Publication Date
November 15, 1987
Publication Information
Publication: Astrophysical Journal, Part 1
Volume: 322
ISSN: 0004-637X
Subject Category
SOLAR PHYSICS
Funding Number(s)
CONTRACT_GRANT: AF-AFOSR-83-0019
CONTRACT_GRANT: N00014-86-K-0068
CONTRACT_GRANT: NAG5-501
CONTRACT_GRANT: NAS5-23758
Distribution Limits
Public
Copyright
Other