HEAD Division Meeting 1999, April 1999
Session 30. Other
Poster, Wednesday, April 14, 1999, 8:30am Wed. - 2:00pm Thurs., Gold Room

## [30.01] The X-ray MEGA'' Observing Campaign

Michael F. Corcoran (GSFC/LHEA/USRA)

The \textit{Einstein}, \textit{ROSAT} and \textit{ASCA} X-ray observatories have made substantial progress towards an understanding of X-ray emission from massive stars, having established (for example) that the observed X-ray luminosity is proportional to stellar bolometric luminosity for the OB stars, or that X-ray variability is relatively rare among massive stars, or that X-ray emission from Wolf-Rayet stars shows unexpectedly large amounts of scatter in their Lx/Lbol relation, or that binary systems like WR 140 and \gamma2 Vel show evidence of X-ray emitting gas produced by the collision of stellar winds. These observations have also raised many unresolved questions: why are some binaries X-ray variables and some not? What causes the scatter in Lx/Lbol for the WR stars? Why are LBVs weak X-ray sources? When is X-ray emission from colliding winds important, and what does that tell us about the nature of the stellar winds in binaries? Modern X-ray observatories raise the exciting possibility of using X-ray emission as a tool to address fundamental questions about the dynamics and chemistry of stellar winds. The X-ray "MEGA" Campaign consists of 50 scientists with interest in developing a full understanding of the phenomena of X-ray emission from hot stars. The purpose of this campaign is to obtain deep X-ray observations of important massive stars and star clusters, along with supporting ground-based observations in order to fully understand the relation between stellar atmospheric phenomena and X-ray emission from hot massive stars. We discuss some recent observing campaigns and results of our observations.

If the author provided an email address or URL for general inquiries, it is as follows:
http://lheawww.gsfc.nasa.gov/users/corcoran/xmega/xmega.html

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