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Astron. Astrophys. 325, 677-684


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Inference of steady stellar wind v(r) laws from optically thin emission lines

I. Idealised analysis for the profile of a single line

J.C. Brown1, L.L. Richardson1, J.P. Cassinelli2, and R. Ignace1

1Department of Physics and Astronomy, University of Glasgow, Glasgow, UK
2Department of Astronomy, University of Wisconsin-Madison, USA

Received 28 August 1996 / Accepted 21 November 1996

Abstract

The form of the profile FORMULA of an emission line from a steady spherical wind of velocity profile v(r) is derived for the case when optical depths are small, when stellar occultation of the wind is neglected, and when v(r) is highly supersonic. It is shown how the resulting integral equation for v(r), given FORMULA , can be inverted to yield v(r) if the line emissivity function j(r) is known.

Solutions are demonstrated for simulated data in the case of a recombination line FORMULA for various trial forms of v(r). The solution is unique provided FORMULA does not change sign anywhere and is remarkably stable against noise in the FORMULA data. The analysis is idealised in the sense that the stellar mass loss rate FORMULA and distance D are assumed known, the solution being then carried out in scaled dimensionless variables. The absolute r-scale of the solution for given FORMULA scales as FORMULA . If this quantity is known the method also yields the stellar radius.

Key words: lines: profile - stars: mass loss - numerical methods

Send offprint requests to: J.C. Brown


© European Southern Observatory (ESO) 1997

Online publication: September 9, 1997
Last change: April 28, 1998
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