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Observational connections between LBV’s and other stars, with emphasis on Wolf-Rayet stars

Published online by Cambridge University Press:  12 April 2016

A. F. J. Moffat ,
L. Drissen  and
C. Robert
A. F. J. Moffat
Affiliation:
Département de Physique, Université de MontréalC.P. 6128, Succ. “A”Montréal, Québec H3C 3J7Canada
L. Drissen
Affiliation:
Département de Physique, Université de MontréalC.P. 6128, Succ. “A”Montréal, Québec H3C 3J7Canada
C. Robert
Affiliation:
Département de Physique, Université de MontréalC.P. 6128, Succ. “A”Montréal, Québec H3C 3J7Canada

Abstract.

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We suggest that the LBV mechanism is an essential step to “force” massive stars (M(ZAMS) ≥ 40M⊙) to finally enter the Wolf-Rayet (W-R) domain in the Hertzsprung-Russel diagram (HRD). Just as massive supergiants show increasing variability as they approach the Humphreys-Davidson (H-D)instability limit (horizontally in the HRD diagram), so the W-R stars show decreasing variability as they recede from the H-D limit (at first horizontally into the WNL domain, then, with their high mass loss rates, plunging irreversably downwards as ever hotter, smaller and fainter, strong-line W-R stars). Among the W-R stars, the luminous WNL subtypes (especially WN8) are the most variable, probably as a consequence of blob ejection in the wind. The underlying mechanism which triggers this ejection is possibly related to wind instabilities and may thus be quite different from the source of variability in luminous supergiants or LBV’s in quiescence, where photospheric effects dominate.

Type
Section I: Main Papers, General Discussions, and Two Panel Discussions
Information
International Astronomical Union Colloquium , Volume 113: Physics of Luminous Blue Variables , 1989 , pp. 229 - 240
Copyright
Copyright © Kluwer 1989

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