The Driving of Hot Star Winds by Andreas A. C. Sander. on Tuesday 22 November

In the regime of hot stars, winds were not seen as a common thing until the

era of UV astronomy. Since we have access to the UV wavelength range, it has

become clear that winds are not an exotic phenomenon limited to some special

objects, but actually ubiquitous among hot and massive stars. The opacities due

to spectral lines are the decisive ingredient that allows hot, massive stars to

launch powerful winds. While the fundamental principles of these so-called

line-driven winds have been realized decades ago, their proper quantitative

prediction is still a major challenge today. Established theoretical and

empirical descriptions have allowed us to make major progress on all

astrophysical scales. However, we are now reaching their limitations as we

still lack various fundamental insights on the nature of hot star winds,

thereby hampering us from drawing deeper conclusions, not least when dealing

with stellar or sub-stellar companions. This has spawned a new generation of

researchers searching for answers with a yet unprecedented level of detail in

observational and new theoretical approaches.

In these proceedings, the fundamental principles of driving hot star winds

will be briefly reviewed. Starting from the classical CAK theory and its

extensions, over Monte Carlo and recent comoving-frame-based simulations, the

different methods to describe and model the acceleration of hot star winds will

be introduced. The review continues with briefly discussing instabilities as

well as qualitative and quantitative insights for OB- and Wolf-Rayet-star

winds. Moreover, the challenges of companions and their impact on

radiation-driven winds are outlined.

arXiv: http://arxiv.org/abs/http://arxiv.org/abs/2211.11457v1