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Hα outbursts of μ Centauri: a clue to the Be phenomenon?

A photoelectric record of circumstellar H-alpha emission in Mu Cen, a mildly active bright southern Be star, is presented. The observations cover a period of about 200 d in 1987. During that time, Mu Cen showed four major outbursts, characterized by an increase of emission intensity from almost 0 to...

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Bibliographic Details
Published in:Astronomy and astrophysics (Berlin) 1993-07, Vol.274 (2), p.356-372
Main Authors: HANUSCHIK, R. W, DACHS, J, BAUDZUS, M, THIMM, G
Format: Article
Language:English
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Summary:A photoelectric record of circumstellar H-alpha emission in Mu Cen, a mildly active bright southern Be star, is presented. The observations cover a period of about 200 d in 1987. During that time, Mu Cen showed four major outbursts, characterized by an increase of emission intensity from almost 0 to 2-4 A equivalent width within 2-5 d. Evidence is presented to the effect that the star is in a state of elevated visual brightness during phases of H-alpha emission activity. It is determined that the radius of the circumstellar disk reaches a maximum value of 4-6 stellar radii during emission maximum, and is smaller before and after maximum. The present observations are interpreted in terms of simple ejection modes. The H-alpha outbursts are likely caused by ejection of matter from a region somewhat above the stellar surface, preferentially in the equatorial plane. It is concluded that Mu Cen represents a prototype of Be star activity which, when enhanced in efficiency by a factor of 2 or 3, can produce quasi-stationary envelopes as observed in many Be stars. (AIAA)
ISSN:0004-6361
1432-0746