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Using the Spitzer IRAC camera we have obtained mid-IR photometry of the redgiant branch stars in the Galactic globular cluster 47 Tuc. About 100 starsshow an excess of mid-infrared light above that expected from theirphotospheric emission. This is plausibly due to dust formation in mass flowingfrom these stars. This mass loss extends down to the level of the horizontalbranch and increases with luminosity. The mass loss is episodic, occurring inonly a fraction of stars at a given luminosity. Using a simple model and ourobservations we derive mass loss rates for these stars. Finally, we obtain thefirst empirical mass loss formula calibrated with observations of Population IIstars. The dependence on luminosity of our mass loss rate is considerablyshallower than the widely used Reimers Law. The results presented here are thefirst from our Spitzer survey of a carefully chosen sample of 17 GalacticGlobular Clusters, spanning the entire metallicity range from about onehundredth up to almost solar.

The First Empirical Mass Loss Law for Population II Giants