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Fast Hα Variations on a Rapidly Rotating Spotted Star

Published online by Cambridge University Press:  25 April 2016

R. D. Robinson  and
A. Collier Cameron
R. D. Robinson
Affiliation:
Anglo-Australian Observatory
A. Collier Cameron
Affiliation:
Institute of Astronomy, Cambridge
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Extract

The star AB Dor (HD 36705) was first identified as an interesting object because of its strong Call H and K emission features (Bidelman and MacConnell 1973; Houk and Cowley 1975). It has a spectral class of G8 and appears to be a single star, since no radial velocity variations have thus far been detected, despite numerous attempts (e.g. Collier 1982; Innis et al. 1985a). Probably the most unusual and important feature about the star is its rapid rotational velocity, with a Vsini of 80 km s-1 (Collier 1982), which is more than 20 times that of a normal star of similar spectral class. AB Dor also shows a substantial photometric wave, commonly interpreted as indicating the presence of starspots. This wave has a typical amplitude of 0.05 to 0.15 magnitudes in V and a period of 0.514 days (e.g. Innis et al. 1985b). Combining this with the Vsini value gives a lower limit of 0.76 R⊙ for the stellar radius, while assuming the radius of a normal G8 dwarf yields an axial inclination of 60° ± 10°.

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Publications of the Astronomical Society of Australia , Volume 6 , Issue 3 , 1986 , pp. 308 - 311
Copyright
Copyright © Astronomical Society of Australia 1986

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