Negative Ions of Hydrogen and the Opacity of Stellar Atmospheres.

Abstract

Compared to the current theory of the atmospheric absorption coefficient, the photo- spheric level is raised considerably in all spectral types later than F5 by including the contribution to the opacity made by the negative ions of hydrogen. Likewise, the dis- continuity at the Balmer limit is greatly reduced, so the values of this quantity ob- served in F stars can be represented without the assumption, advocated by Unsold, of an abundance ratio of hydrogen to metals equal to 50: I. The abundance ratio adopted by Russell and Pamiekoek (H : M = boo: i) appears to be compatible with the observa- tions of the Balmer discontinuity