1997A&A...327..725H

A non-LTE model for stellar winds from Young Stellar Objects (YSOs) was established. This paper presents the results of an extensive set of calculations. Our basic assumptions in the model are: (a) the central sources are early B-type stars with steady mass loss rates and luminosities in the range of 10³∼10⁴ solar luminosity; (b) wind has a spherical symmetric geometry and a pure hydrogen composition; (c) the wind has a constant velocity and constant electron temperature. We adopted the Sobolev approximation to treat the line transfer problem. Our calculations indicate that the matter in stellar wind from YSOs deviates strongly from LTE. We have computed the hydrogen line fluxes and line ratios for a set of model parameters. We find a clear correlation between the line flux ratios of Pfγ/Brα and Brγ/Brα, Paδ/Brα and Brγ/Brα, which are only weakly dependent on the physical conditions of stellar winds and central sources. These relationships can be applied to estimate the foreground extinction of YSOs.