On the decoupling and reaccretion of low density, line-driven winds

Abstract

The flow generated by low-density radiatively driven winds which decouple their gas and radiation fields is discussed. In particular we concentrate on flow which is still bound to the star and can therefore reaccrete. The wind decelerates after decoupling and eventually stalls. A shell of gas is generated, and we find that this shell is unstable and contracts back to the star with periods of hours to days. We find that the pulsating shells may be difficult to observe, as their emission is variable and the maximum emission at H-alpha (of ~1% of the continuum) occurs over a small fraction of the shell cycle.