The Slow Winds of A-Type Supergiants

TL;DR

This paper investigates the conditions under which A-type supergiants exhibit slow stellar winds, revealing that certain parameters can lead to slow wind solutions even at low rotational speeds.

Contribution

It demonstrates that the slow wind solution can exist across the entire star for A-type supergiants under specific line-force parameters, expanding understanding of stellar wind behaviors.

Findings

Slow wind solutions can occur at low or zero rotation when ta 0.25.

Density and velocity profiles of winds are characterized.

Potential observational signatures are discussed.

Abstract

The line driven- and rotation modulated-wind theory predicts an alternative slow solution, besides from the standard m-CAK solution, when the rotational velocity is close to the critical velocity. We study the behaviour of the winds of A-type supergiants (Asg) and show that under particular conditions, e.g., when the \delta line-force parameter is about 0.25, the slow solution could exist over the whole star, even for the cases when the rotational speed is slow or zero. We discuss density and velocity profiles as well as possible observational counterparts.