Mass loss rates inferred from mid-IR color excesses of LMC and SMC O stars

Abstract

We use a combination of VJHK and Spitzer} [3.6], [5.8] and [8.0] photometry, to determine IR excesses in a sample of LMC and SMC O stars. This sample is ideal for determining excesses because: 1) the distances to the stars, and hence their luminosities, are well-determined, and; 2) the very small line of sight reddenings minimize the uncertainties introduced by extinction corrections. We find IR excesses much larger than expected from Vink et al. (2001) mass loss rates. This is in contrast to previous wind line analyses for many of the LMC stars which suggest mass loss rates much less than the Vink et al. predictions. ogether, these results indicate that the winds of the LMC and SMC O stars are strongly structured (clumped).