A Search for Diffuse X-Ray Emission from OB Associations

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Session 110 -- Open Clusters
Display presentation, Saturday, January 15, 9:30-6:45, Salons I/II Room (Crystal Gateway)

[110.12] A Search for Diffuse X-Ray Emission from OB Associations

F. Buls, J.-P. Caillault (University of Georgia)

We report on our search for diffuse emission from OB associations observed with the Einstein IPC. Our sample includes nine associations; only two, Ser~OB2 and Car~OB2, show any evidence for significant unresolved extended emission. Using extinctions and distances taken from Humphreys (1987) and assuming a RS thermal bremsstrahlung emission spectrum with T $\sim$ 6~x~10$^6$~K, we find that the X-ray luminosities of the two regions range from $\sim$~10$^{32}$ to $\sim$~10$^{33}$ergs~s$^{-1}$, comparable to the value claimed by Fabian \& Stewart (1983) for a similar region in Cep~OB3. Although the emission could be truly diffuse (i.e., the result of non-radiative heating of the ambient gas by the association members), we consider the possibility of unresolved point sources as still tenable. To further elucidate this latter possibility we have ROSAT HRI observations planned for next year. \ls Partial support for this project has been provided by NASA through grant NAG8-148.

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