On the nature of the S stars in the Galactic Center

Abstract

Davies and King have suggested that the bright stars observed on short-period orbits about Sgr A* (``S stars'') are old, low-mass stripped AGB stars rather than young, high-mass main-sequence stars. If the observationally inferred effective temperatures and luminosities of these stars are correct, however, then DK have grossly overestimated the post-AGB lifetimes and hence underestimated the production rate in steady state. In fact, the total mass in stars stripped over the age of the Galaxy would exceed that of the stellar cusp bound to Sgr A*. We take issue also with Davies & King's estimates of the energetics involved in capturing the stars onto their present orbits.