AAS Meeting #194 - Chicago, Illinois, May/June 1999
Session 12. Extra Galactic Star Clusters: From Ancient Globulars to Young Star Clusters
Display, Monday, May 31, 1999, 9:20am-6:30pm, Southwest Exhibit Hall

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[12.03] The Age and Mass of Super Star Cluster F in M82

L.J. Smith (University College London), J.S. Gallagher (University of Wisconsin-Madison)

M82 is one of the nearest examples of a spectacular starburst galaxy and contains hundreds of super star clusters (SSCs). We present a detailed study of one of these clusters (SSC F) based on optical spectroscopy obtained at the 4.2\,m William Herschel Telescope at resolutions of 1.6\,Å\ and 10\,km\,s-1. We derive MV=-16.5 for SSC F indicating that it is one of the most luminous and hence most massive clusters known. The blue spectrum (3250--5540\,Å) shows features typical of mid-B stars, and we derive an age of 60±0\,Myr by comparison with theoretical model cluster spectra using the {\sc PEGASE} spectral synthesis code. The red spectral region contains numerous weak metal absorption lines and a strong Ca\,II triplet arising in cool supergiants. The brightness and compactness of SSC F make it an ideal candidate for measuring the line of sight velocity dispersion, and hence obtaining the dynamical mass of the cluster. We present the results of such an investigation based on echelle spectroscopy of SSC F in the region of the Ca\,II triplet. We discuss whether our derived parameters are consistent with SSC F being able to survive to become a globular cluster.

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