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,
Received 28 August 1996 / Accepted 21 November 1996
The form of the profile 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 , 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 for various trial forms of v(r). The solution is unique provided does not change sign anywhere and is remarkably stable against noise in the data. The analysis is idealised in the sense that the stellar mass loss rate 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 scales as . If this quantity is known the method also yields the stellar radius.
Key words: lines: profile - stars: mass loss - numerical methods
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© European Southern Observatory (ESO) 1997
Online publication: September 9, 1997