NLTE wind models of hot subdwarf stars

TL;DR

This paper develops NLTE stellar wind models for hot subdwarf stars, revealing the importance of CNO elements and the impact of X-rays and instabilities on wind properties.

Contribution

It introduces comprehensive NLTE wind models for a broad range of hot subdwarf stars, highlighting the role of CNO elements and wind instabilities in their mass-loss processes.

Findings

CNO elements are key drivers of subdwarf winds.

X-rays and instabilities significantly affect wind structure.

A portion of the wind can become very hot due to line-driven instabilities.

Abstract

We calculate NLTE models of stellar winds of hot compact stars (central stars of planetary nebulae and subdwarf stars). The studied range of subdwarf parameters is selected to cover a large part of these stars. The models predict the wind hydrodynamical structure and provide mass-loss rates for different abundances. Our models show that CNO elements are important drivers of subdwarf winds, especially for low-luminosity stars. We study the effect of X-rays and instabilities on these winds. Due to the line-driven wind instability, a significant part of the wind could be very hot.