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Astron. Astrophys. 325, 677-684 (1997)

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Inference of steady stellar wind [FORMULA] laws from optically thin emission lines

I. Idealised analysis for the profile of a single line

J.C. Brown 1, L.L. Richardson 1, J.P. Cassinelli 2 and R. Ignace 1

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

Received 28 August 1996 / Accepted 21 November 1996


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

Solutions are demonstrated for simulated data in the case of a recombination line [FORMULA] for various trial forms of [FORMULA]. 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


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© European Southern Observatory (ESO) 1997

Online publication: April 28, 1998