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[52.15] Mass Loss in Globular Clusters: Large-Sample Analysis of H-alpha Emission in M15 Giant Stars

P. Cargile, K. Gebhardt, C. Sneden (U. Texas, Austin), C. A. Pilachowski (Indiana U.)

We are using Fabry-Perot imaging to investigate the H-alpha line in hundreds of red giant stars in M15. Cohen (1976) first drew attention to the presence of emission wings of H-alpha lines of metal poor field and globular cluster stars, and Smith & Dupree (1988) explored the dependence of H-alpha emission on luminosity of field halo giants. In a number of papers, comments have been made about the profiles of these lines in individual globular cluster stars, but a systematic large-sample survey has yet to be carried out. In the early stages if this survey, we compare the Fabry-Perot data to high resolution spectra obtained with the Keck I HIRES and WIYN 3.5-meter telescope with the Hydra multi-object spectrograph. We look at the presence of these emission wings at three different epochs to better understand the variability of emission. We then plot the color-magnitude diagram from HST photometric data to locate the position of these stars on the red giant branch. This study will yield valuable data toward understanding the evolution of red giants and their effects on the dynamics of their parent globular cluster.

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Bulletin of the American Astronomical Society, 35#5
© 2003. The American Astronomical Soceity.