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X-ray/microwave relation of different types of active starsCoronal active stars of seven classes between spectral types F and M, single and double, are compared in their quiescent radio and X-ray luminosities L(R) and L(X). We find, largely independent of stellar class, log L(X) is less than about log L(R) + 15.5. This general relation points to an intimate connection between the nonthermal, energetic electrons causing the radio emission and the bulk plasma of the corona responsible for thermal X-rays. The relation, observed over six orders of magnitude, suggests that the heating mechanism necessarily involves particle acceleration. We derive requirements for simple models based on optically thin gyrosynchrotron emission of mildly relativistic electrons and thermal X-rays from the bulk plasma. We discuss the possibility that a portion of the accelerated particles heats the ambient plasma by collisions. More likely, plasma heating and particle acceleration may occur in parallel and in the same process, but at a fixed ratio.
Document ID
19930047865
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Guedel, Manuel
(Joint Inst. for Laboratory Astrophysics Boulder, CO, United States)
Benz, Arnold O.
(Zuerich Eidgenoessische Technische Hochschule, Zurich, Switzerland)
Date Acquired
August 16, 2013
Publication Date
March 10, 1993
Publication Information
Publication: Astrophysical Journal, Part 2 - Letters
Volume: 405
Issue: 2
ISSN: 0004-637X
Subject Category
Astrophysics
Accession Number
93A31862
Funding Number(s)
CONTRACT_GRANT: SNSF-20,34045,92
CONTRACT_GRANT: SNSF-8220-033360
CONTRACT_GRANT: NAG5-1887
Distribution Limits
Public
Copyright
Other

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