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Paper: The Stellar Winds of Galactic Early B Supergiants
Volume: 361, Active OB-Stars: Laboratories For Stellar and Circumstellar Physics
Page: 172
Authors: Searle, S.C.; Prinja, R.K.; Massa, D.
Abstract: Optical and ultraviolet spectroscopic analysis of a sample of Galactic B supergiants is presented here. Fundamental parameters such as temperature, luminosity, mass loss rate and CNO abundances are derived for individual stars using the non-LTE, line-blanketed model atmosphere code of Hillier & Miller (1998). The implications of this Galactic B supergiant temperature scale and the derived mass loss rates and CNO abundances are discussed and compared to other results.

Empirical analysis of the ionization conditions of early B supergiant winds has also been carried out (based on SEI modeling) and compared to model predictions from the stellar atmosphere code of Hillier & Miller (1998). Intriguingly we find that the values of the empirical qi's are much lower than expected, with none of the ions approaching unity. We discuss our most recent findings and their implications for clumping and structure in the wind. In particular we argue that these results point for a downward revision in mass loss rates by at least an order of magnitude. There is therefore a clear need to review mass loss rate determinations for massive stars.

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