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On the enigma of FK ComaeStellar chromospheric and coronal activity appears ubiquitous among late type stars to the left of the TR-wind boundary line (Linksy and Haisch 1979). The level of activity as measured by the X-ray surface flux is linearly proportional to the stellar angular velocity, with the exception of slowly rotating dwarfs (Walter 1981, 1982; Walter and Bowyer 1981). The peculiar rapidly rotating G giant FK Comae (Merrill 1948) appears to fit into this pattern. Line widths indicate V sin i = 120 + or - 20 km s(-1) (Bopp and Stencel 1981). FK Comae has strong Ca II H and K and H alpha emission, strong transition region UV lines (Bopp and Stencel 1981), and an X-ray surface flux in good agreement with its rapid rotation (Walter 1981). Yet, FK Comae is an enigmatic star. It is a rapid rotator, but it is not clear why it is a rapid rotator. There is no direct evidence for duplicity; indeed, the upper limit of 20 km s(-1) on the K velocity puts tight constraints on any binary configuration, especially if sin i approx 1, as indicated by the large V sin i. Bopp and Stencel (1981) have suggested that FK Comae is an example of a coalesced W UMa system (Webbink 1976), wherein the orbital angular momentum has become rotational angular momentum of the coalesced star.
Document ID
Document Type
Conference Paper
Walter, F. (Joint Inst. for Lab. Astrophysics Boulder, CO, United States)
Basri, G. (California Univ. Berkeley, United States)
Date Acquired
August 11, 2013
Publication Date
January 1, 1981
Publication Information
Publication: Smithsonian Astrophysics Observatory 2nd Cambridge Workshop on Cool Stars, Stellar Systems, and the Sun, Vol. 1
Subject Category
Funding Number(s)
Distribution Limits
Work of the US Gov. Public Use Permitted.

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IDRelationTitle19830012575Analytic PrimarySecond Cambridge Workshop on Cool Stars, Stellar Systems, and the Sun, volume 1