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Advances in modeling of Wolf-Rayet stars

Published online by Cambridge University Press:  26 May 2016

D. John Hillier
D. John Hillier*
Affiliation:
Department of Physics and Astronomy, University of Pittsburgh, 3941 O'Hara Street, Pittsburgh, PA 15260, USA

Abstract

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Due to advances in computer power and numerical techniques non-LTE line-blanketing calculations for Wolf-Rayet (WR) stars are now routine. The incorporation of blanketing has led to significant improvements in spectral analyses, and to a systematic increase in the derived WR luminosities. To make further progress we need to understand the distribution, structure, and strength of inhomogeneities in the stellar wind, and in turn, how these influence diagnostics of WR stellar parameters, and radiative driving. Further, we need to understand the physical process that initiates mass loss in WR stars. Problems with existing wind calculations are examined, and the difficulty of observationally determining the shape of the velocity law around the sonic point is discussed. To determine the wind dynamics around the sonic point, it is essential to include ions with ionization potentials in excess of 300 eV. A recent study of the 07 Iaf+ star AV 83 is discussed. The analysis indicates the existence of a clumped wind, and a relatively slow wind acceleration with the velocity law characterized by β = 2. The importance of extreme Of stars, for understanding both WR and O-type star winds, is stressed. Spectra of such stars show numerous photospheric and wind features, allowing the entire wind to be probed observationally.

Type
Part 1. Atmospheres of Massive Stars
Information
Symposium - International Astronomical Union , Volume 212: A Massive Star Odyssey: From Main Sequence to Supernova , 2003 , pp. 70 - 79
Copyright
Copyright © Astronomical Society of the Pacific 2003 

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