College of Science

SEMINAR: David Cohen [Swarthmore]

X-ray Emission from Massive Stars

May 15, 2014 10:50 AM to May 15, 2014 12:00 PM at Building 8, Room 241

David Cohen

Massive stars - like the three belt stars in Orion - are rare but very luminous, emitting up to a million times more radiant energy than the Sun. The momentum in this light actually drives a strong stellar wind at thousands of km/s off the surfaces of these stars. These radiation-driven winds are so strong that massive stars can lose an appreciable fraction of their initial mass over the course of their lifetimes. My group has analyzed the X-ray emission, including spectral line profiles, of a dozen massive stars measured with the Chandra X-ray Observatory to study X-ray production and the wind properties of these stars. In this talk I will show how the X-rays provide information about the fundamental physics of radiation-driven winds and allow us also to measure the clumpiness of the winds and their mass-loss rates.

David Cohen is an Associate Professor of Astronomy at Swarthmore College in Pennsylvania. For more information about his work, see his website at

10:50 a.m. Refreshments
11:00 a.m. Seminar

Building 8 - Room 241