Self-consistent models of Wolf-Rayet stars as helium stars with optically thick winds

Mariko Kato, Icko Iben

Research output: Contribution to journalArticle

30 Citations (Scopus)

Abstract

We propose a helium star with a steady, optically thick wind as a first-order model for Wolf-Rayet stars. Using an enhanced opacity which is guided by results of recent opacity calculations, we obtain self-consistent solutions which are made up of an inner helium-burning core in hydrostatic equilibrium and an outer radiative envelope through which a steady state wind is accelerated. Our surface is at optical depth near unity. The models are of homogeneous composition (primarily helium) and are of mass in the range 9-30 M. In the most massive model, the momentum of the mass flow exceeds the photon momentum at the photosphere by a factor of 30. Terminal wind velocities are of order 1000 km s-1; these velocities are lower limits, as we neglect line-driven wind acceleration above the photosphere. For an appropriate choice of the opacity enhancement law, models of different mass define a relationship between the mass-loss rate [log M (M yr-1) from -5.5 to -3.5] and the photospheric temperature (7ph = 2-9 × 104 K) which is consistent with observed data. We also find a forbidden region in the low-temperature part of the H-R diagram where no thick wind solutions exist.

Original languageEnglish
Pages (from-to)305-312
Number of pages8
JournalAstrophysical Journal
Volume394
Issue number1
Publication statusPublished - 1992

Fingerprint

Wolf-Rayet stars
B stars
helium
opacity
photosphere
momentum
terminal velocity
wind velocity
mass flow
hydrostatics
optical thickness
optical depth
low speed
unity
envelopes
diagram
diagrams
augmentation
photons
temperature

Keywords

  • Stars: chemically peculiar
  • Stars: interiors
  • Stars: mass loss
  • Stars: Wolf-Rayet

ASJC Scopus subject areas

  • Space and Planetary Science

Cite this

Self-consistent models of Wolf-Rayet stars as helium stars with optically thick winds. / Kato, Mariko; Iben, Icko.

In: Astrophysical Journal, Vol. 394, No. 1, 1992, p. 305-312.

Research output: Contribution to journalArticle

Kato, Mariko ; Iben, Icko. / Self-consistent models of Wolf-Rayet stars as helium stars with optically thick winds. In: Astrophysical Journal. 1992 ; Vol. 394, No. 1. pp. 305-312.
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