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arXiv · 1101.1095

Fundamental parameters, integrated RGB mass loss and dust production in the Galactic globular cluster 47 Tucanae

Iain McDonald·Martha L. Boyer·Jacco Th. van Loon·Albert A. Zijlstra·Joseph L. Hora·Brian Babler·Miwa Block·Karl Gordon·Marilyn Meade·Margaret Meixner·Karl Misselt·Thomas Robitaille·Marta Sewilo·Bernie Shiao·Barbara Whitney
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Abstract

Fundamental parameters and time-evolution of mass loss are investigated for post-main-sequence stars in the Galactic globular cluster 47 Tucanae (NGC 104). This is accomplished by fitting spectral energy distributions (SEDs) to existing optical and infrared photometry and spectroscopy, to produce a true Hertzsprung--Russell diagram. We confirm the cluster's distance as 4611 (+213, -200) pc and age as 12 +/- 1 Gyr. Horizontal branch models appear to confirm that no more RGB mass loss occurs in 47 Tuc than in the more-metal-poor omega Centauri, though difficulties arise due to inconsistencies between the models. Using our SEDs, we identify those stars which exhibit infrared excess, finding excess only among the brightest giants: dusty mass loss begins at a luminosity of ~ 1000 Lsun, becoming ubiquitous above 2000 Lsun. Recent claims of dust production around lower-luminosity giants cannot be reproduced, despite using the same archival Spitzer imagery.

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Iain McDonald, Martha L. Boyer, Jacco Th. van Loon, Albert A. Zijlstra, Joseph L. Hora, Brian Babler, Miwa Block, Karl Gordon, Marilyn Meade, Margaret Meixner, Karl Misselt, Thomas Robitaille, Marta Sewilo, Bernie Shiao, Barbara Whitney. 2011-01-05. Fundamental parameters, integrated RGB mass loss and dust production in the Galactic globular cluster 47 Tucanae. https://doi.org/10.1088/0067-0049/193/2/23

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