Fundamental parameters, integrated red giant branch mass loss, and dust production in the galactic globular cluster 47 Tucanae

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 red giant branch mass loss occurs in 47 Tuc than in the more metal-poor ω Centauri, though difficulties arise due to inconsistencies between the models. Using our SEDs, we identify those stars that exhibit infrared excess, finding excess only among the brightest giants: dusty mass loss begins at a luminosity of ∼ 1000 L ⊙, becoming ubiquitous above L = 2000 L ⊙. Recent claims of dust production around lower-luminosity giants cannot be reproduced, despite using the same archival Spitzer imagery. © 2011. The American Astronomical Society. All rights reserved.