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Emission-line-profile variability as a contraint on the structure and dynamics of hot star winds

Published online by Cambridge University Press:  26 May 2016

Luc Dessart  and
Stanley P. Owocki
Luc Dessart
Affiliation:
Sterrekundig Instituut, Universiteit Utrecht, Princetonplein 5, NL-3584 CC Utrecht, Nederland
Stanley P. Owocki
Affiliation:
Bartol Research Institute, University of Delaware, Newark, DE 19716, USA

Abstract

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We present theoretical calculations of emission-line-profile variability (LPV), based on radiation hydrodynamics simulations of the infamous radiative instability of hot star winds. We demonstrate that spherically symmetric wind structures (shells) cannot account for the observed profile variability at line center. Hence, we resort to a model that breaks-up the wind volume into a number of independent star-centered cones. The essential approximation made here is that each of these cones can be described by a structure calculated with a one-dimensional (1d) radiation hydrodynamics model. Such pseudo-3d ‘patch’-method leads to a satisfactory reproduction of the fundamental characteristics of LPV observed in O-type and Wolf-Rayet star optical spectra: the low-level fluctuations in the profile centre region, a migration of variable sub-peaks from line center to edge, that mimics the underlying wind acceleration. Our method highlights the correlation between the velocity scale of profile sub-peaks at line center and the lateral extent of wind structures, while at line edge it reflects the intrinsic radial velocity dispersion of emitting clumps. However, our model fails to reproduce the increase in this characteristic velocity scale from line center to edge, which we believe is a shortcoming of our purely 1d hydrodynamics approach.

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. 168 - 169
Copyright
Copyright © Astronomical Society of the Pacific 2003 

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