Abbott Wavetriggered Runaway in Line-driven Winds from Stars and Accretion Disks

摘要

Line-driven winds from stars and accretion disks are accelerated by scattering in numerous line tran- sitions. The wind is believed to adopt a unique critical solution out of the infinite variety of shallow and steep solutions. We study the inherent dynamics of the transition toward the critical wind. A new runaway wind mechanism is analyzed in terms of radiative acoustic (Abbott) waves, which are responsible for shaping the wind velocity law and fixing the mass loss. Three different flow types result depending on the location of perturbations. First, if the shallow solution is perturbed sufficiently far downstream, a single critical point forms in the flow, which is a barrier for Abbott waves, and the solu- tion tends to the critical one.