The most striking challenges in the theory of massive star winds

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• Brankica Surlan Kubatova
• Wednesday 25 April 2018, 14:30-15:30
• Physics West 117.

If you have a question about this talk, please contact Sean McGee.

Massive stars (M > 10 Msun) belong to the most important cosmic engines releasing energy and chemically processed material via intense mass-loss and explosions. To understand the evolution of the Universe it is crucial to comprehend the physical properties and the entire evolution of massive stars. The evolution of massive stars is highly regulated by huge amounts of mass expelled from their surfaces by means of wind outflows (i.e. stellar winds). These stellar winds crucially determine how such massive stars evolve through their entire lives and finally how they die. There are several observational diagnostics which are commonly used to determine the wind mass-loss rate. Typically used tracers of the mass-loss rate are the shape of the emission line profiles in the X-ray domain, the strength of the ultraviolet P Cygni lines in the UV domain, the Hα emission line in the optical region, and the strength of the infrared recombination lines and radio excess. Ideally, all these diagnostics should give the same mass-loss rate for the same star, which should also agree with theoretical predictions. However, these values may differ by one or more orders of magnitude. Consequently, this can have a drastic effect for the predicted (and actual) evolution of massive stars. These discrepancies between the individual mass-loss diagnostics may most likely be attributed to the influence of small scale wind inhomogeneities (i.e. clumping), which are one of the most important ingredients for reliable mass- loss rate determination. In this talk I’ll present the most striking challenges in observational and theoretical studies of massive star winds. I’ll discuss the critical uncertainties in mass-loss rate determination that are mostly connected with clumping. I’ll also present the new sophisticated 3-D model of radiation transfer in inhomogeneous expanding media which we developed in order to elucidate the physics of stellar winds and improve classical empiric mass-loss rate diagnostics.

This talk is part of the Astrophysics Talks Series series.

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• Astrophysics Talks Series
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