The Continuous Absoprtion Coefficient of the Negative Hydrogen Molecular Ion.

Abstract

In the atmospheres of cool stars, most of the hydrogen is in molecular form and continuous absorption by H2- is of importance in determining opacities, similarly to the absorption by II- in hotter stars. Calculations are reported for free-free transitions, using the Ohmura method with exchange phase shifts obtained by Massey and Ridley; the absorption coefficient is found to take values between one-half and one-quarter of those for H-. The bound-free contribution to the opacity is almost certainly negligibly small.