Prof. David Cohen – Swarthmore College
“X-ray Emission from Massive Stars”
The strong X-ray emission from the most massive stars in the Galaxy was a surprising discovery of the first generation of X-ray telescopes in the late 1970s. Massive stars, unlike the Sun, are not supposed to have a magnetic dynamo, and thus were not expected to be X-ray sources at all. Now, nearly 30 years later, the newest generation of X-ray telescopes, with high spectral resolution, have shown that massive star X-rays are very different from solar-type X-rays. My students and I have worked on two different models – one stellar-wind based and one hybrid magnetic-wind model that applies to very young massive stars – which we have used to help us understand the new X-ray observations of massive stars with NASA’s Chandra X-ray Telescope. I will discuss the basics of stellar X-ray emission, present the new Chandra data and our fits to it, and briefly describe – using numerical simulations – the hybrid magnetic-wind model.