Coronal winds powered by radiative driving

TL;DR

This paper presents a revised two-component model for weak-wind phenomena in late-type O dwarfs, showing how radiative and coronal processes drive stellar outflows and influence wind structure and velocity.

Contribution

It introduces a new phenomenological model that combines radiative driving and coronal heating to explain weak stellar winds in late-type O dwarfs.

Findings

Coronal gas heats to ~3 million K at radii > 1.4 R.

Cool, dense clumps are confined with a filling factor of ~0.02.

The wind reaches a terminal velocity of ~980 km/s.

Abstract

A two-component phenomenological model developed originally for zeta Puppis is revised in order to model the outflows of late-type O dwarfs that exhibit the weak-wind phenomenon. With the theory's standard parameters for a generic weak-wind star, the ambient gas is heated to coronal temperatures ~ 3 x 10^{6}K at radii > 1.4 R, with cool radiativly-driven gas being then confined to dense clumps with filling factor ~ 0.02. Radiative driving ceases at radius ~ 2.1R when the clumps are finally destroyed by heat conduction from the coronal gas. Thereafter, the outflow is a pure coronal wind, which cools and decelerates reaching infinity with terminal velocity ~ 980$ km/ s.