X-ray emission from the winds of hot stars. II

Abstract

Equations are derived governing the structure and X-ray emission characteristics of a phenomenological model for the limiting amplitude state reached by unstable line-driven winds. Expressions for the equation of motion, shock speed, mass flux, radiative driving, shock spacing, X-ray emission, and efficiency are stated. Radiatively driven shocks are conjectured to result from the amplification of unstable waves and to survive until shadowing by following shocks compels their decay. X-ray emission is predicted to continue far out into the nearly terminal flow, with the effects of self-absorption not expected to be prominent. The theory is used to discuss briefly the time-averaged velocity law for winds and then to calculate models and X-ray luminosities for individual stars.