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Starspots on flare starsSizes of starspots on flare stars can be derived from the author's convection-cell hypothesis. The sizes are in fair agreement with those observed on YY Gem, CC Eri, and BY Dra by Bopp and Evans (1973). The hypothesis predicts that periodic brightness variations due to starspots are restricted to stars brighter than a critical absolute visual magnitude. A convective model of a starspot on YY Gem has been computed, assuming that the missing flux is in the form of Alfven waves. It is found that the surface field must exceed 10,000 G, and is probably less than about 30,000 G. With a surface field of 20,000 G, the effective temperature of the spot is in the range from 1590 to 1890 K, depending on the field gradient. These figures are to be compared with an effective temperature of 2000 K estimated from observations by Bopp and Evans. Efficient dynamo action is shown to be a possible mechanism for generating such large surface fields. There is a possibility that tidal effects may influence starspot formation.
Document ID
19740059161
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Mullan, D. J.
(Franklin Institute, Bartol Research Foundation, Swarthmore Pa., United States)
Date Acquired
August 7, 2013
Publication Date
August 15, 1974
Publication Information
Publication: Astrophysical Journal
Volume: 192
Subject Category
Space Sciences
Accession Number
74A41911
Funding Number(s)
CONTRACT_GRANT: NGR-39-005-066
Distribution Limits
Public
Copyright
Other

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