SCYON Abstract

Received on January 20 2011

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

Authors	Iain McDonald (¹), M.L. Boyer (²), J.Th. van Loon (³), A.A. Zijlstra (¹), J.L. Hora (⁴), B. Babler (⁵), M. Block (⁶), K. Gordon (²), M. Meade (⁵), M. Meixner (²), K. Misselt (⁶), T. Robitaille (⁴), M. Sewilo (²), B. Shiao (²), and B. Whitney(²)
Affiliation	(¹) Jodrell Bank Centre for Astrophysics, Alan Turing Building, Manchester, M13 9PL, UK (²) STScI, 3700 San Martin Drive, Baltimore, MD 21218, USA (³) Lennard-Jones Laboratories, Keele University, ST5 5BG, UK (⁴) Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, MS 65, Cambridge, MA 02138-1516, USA (⁵) Department of Astronomy, University of Wisconsin, Madison, 475 North Charter Street, Madison, WI 53706-1582, USA (⁶) Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tuscon, AZ 85721, USA
Accepted by	Astrophysical Journal Supplement Series
Contact	mcdonald@jb.man.ac.uk
URL	http://xxx.soton.ac.uk/abs/1101.1095
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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 d = 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 L = 2000 Lsun. Recent claims of dust production around lower-luminosity giants cannot be reproduced, despite using the same archival Spitzer imagery.