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Adiabatic heating in impulsive solar flaresA study is made of adiabatic heating in two impulsive solar flares on the basis of dynamic X-ray spectra in the 28-254 keV range, H-alpha, microwave, and meter-wave radio observations. It is found that the X-ray spectra of the events are like those of thermal bremsstrahlung from single-temperature plasmas in the 10-60 keV range if photospheric albedo is taken into account. The temperature-emission correlation indicates adiabatic compression followed by adiabatic expansion and that the electron distribution remains isotropic. H-alpha data suggest compressive energy transfer. The projected areas and volumes of the flares are estimated assuming that X-ray and microwave emissions are produced in a single thermal plasma. Electron densities of about 10 to the 9th/cu cm are found for homogeneous, spherically symmetric sources. It is noted that the strong self-absorption of hot-plasma gyrosynchrotron radiation reveals low magnetic field strengths.
Document ID
19780061650
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Maetzler, C.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Bai, T.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Crannell, C. J.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Frost, K. J.
(NASA Goddard Space Flight Center Greenbelt, Md., United States)
Date Acquired
August 9, 2013
Publication Date
August 1, 1978
Publication Information
Publication: Astrophysical Journal
Subject Category
Solar Physics
Accession Number
78A45559
Funding Number(s)
CONTRACT_GRANT: NGR-21-002-316
Distribution Limits
Public
Copyright
Other

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