Non-LTE modelling of the He l 10830 Å line in early-type main sequence stars

Abstract

The near-IR He I 10830 Å transition is a highly sensitive diagnostic for non-LTE effects in astrophysical plasmas. So far, non-LTE line-formation computations have failed to quantitatively reproduce observations of this line in the entire range of early-A to late-O main sequence stars. It is shown that the non-LTE modelling was insufficient, for the most part, either because of inaccurate photoionization cross-sections for the 2s 3S state or because of neglecting line blocking. New calculations based on state-of-the-art atomic data give excellent agreement with observation for the He I 10830 Å feature, while profiles of the He I lines in the visual are retained. © ESO 2005.