Non-LTE modelling of the HeI 10830A line in early-type main sequence stars

Abstract

The near-IR HeI 10830A transition is a highly sensitive diagnostic for non-LTE effects in the helium atom. 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 the neglect of line blocking. New calculations based on state-of-the-art atomic data give excellent agreement with observation for the HeI 10830 A feature, while profiles of the HeI lines in the visual are retained.

4 pages, 4 figures; accepted for publication in A&A

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