Mass loss from O subdwarfs.

Abstract

The P Cygni profiles are reproduced by comoving frame calculations, and a determination is made of the wind parameters. Lower limits of mass loss for these stars (HD 49798 and HD 128220 B) are derived, and upper limits for all four objects are estimated on the basis of general considerations. The empirical results are compared with the available theories. The mass loss rates are found to agree reasonably well with the predictions of the fluctuation theory. It is concluded that the theory of radiation-driven winds cannot explain why the mass fluxes from subluminous stars are distinctly smaller than from supergiants.