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A source for mass-loss instabilities in LBV’s – the case of P Cygni
Published online by Cambridge University Press: 12 April 2016
Extract
Since the basic mechanisms that produce photometric variations, shell ejections, and eruptions of LBV’s are still unknown, it is worthwhile to investigate whether instabilities can occur when the improved self-consistent NLTE treatment of radiation-driven winds (see Pauldrach et al. 1986, Pauldrach 1987, Puis 1987, Pauldrach & Herrero 1988) is applied to objects lying in the LBV part of the H-R diagram. The motivation is obvious: LBV’s have lost considerable fractions of their initial masses and hence have L/M ratios close to the Eddington limit. For such objects, radiation-driven wind theory predicts not only a strong dependence of the mass-loss rate on the self-consistently calculated parameters k, α, and δ, which result from the NLTE occupation numbers of the 133 ions contributing to the line force, but also on Γ (= L/LEdd): Ṁ ~ k1/(α – δ) (1 – Γ)(α – 1)/(α – δ). Here we investigate the dependences of Ṁ on M (through Γ) and on the physical environment of the atmosphere (through k, α, δ) separately. The calculations are performed over a large model grid of stellar parameters for P Cyg, a typical LBV (see Fig. 1).
- Type
- Section II: Poster Papers, A Brief List of Catalogs, and Index
- Information
- International Astronomical Union Colloquium , Volume 113: Physics of Luminous Blue Variables , 1989 , pp. 261 - 262
- Copyright
- Copyright © Kluwer 1989