[Normal Stars and WD -- Oral ]

The Shocking Truth about Massive Stars

Lidia Oskinova, University of Potsdam
W.-R. Hamann (Uni Potsdam), A. Feldmeier (Uni Potsdam)

X-ray emission from massive stars manifests the dynamic nature of their powerful stellar winds. Observations made by Chandra and XMM-Newton in the last decade, and follow up discoveries revolutionized our perception of stellar winds. I will show that Chandra spectroscopy is a perfect tool toanswer the most pressing problems in wind research, such as inferring the parameters of wind clumping. This is pre-requisite to obtain empirically correct stellar mass-loss rate - a key ingredient of stellar feedback.X-rays also provide the best means to study the physics of stellar wind. Shocks, magnetic fields, rotation, which are typically ignored in classical models, must be accounted for to understand X-rays in massive stars. I will briefly review our current work based on the analyses of the latest Chandra and XMM-Newton observations of stars with spectral typesfrom B to WO. We have fairly good ideas how X-rays are produced in O stars via wind shocks. We have the suspicion that some additional mechanisms should be at work in B stars, but we have little understanding yet about X-rays in WR stars. The latter are immediate SN and GRB progenitors. I will consider a possible scenario to explain the X-rays from WR stars, and discuss its implication for the physics of progenitors and their circumstellar environment.