SIMBAD references

Stellar counts in Baade's window field of the Galactic Bulge are used to estimate the helium content of the metal rich stars in the Bulge. From the number ratio R_c of clump to red giant stars, the helium content is estimated to be in the range 0.30-0.35, which corresponds to a helium enrichment parameter {DELTA}Y/{DELTA}Z=2 to 3, with 3 being a strict upper limit. The ratio R_c is instead shown to be rather insensitive to the age of a stellar population, for ages in excess of ∼1 Gyr. Since there is no trace of such young stars in the Bulge, it is concluded that the high observed value of R_c is not due to an age effect, but instead it is the result of the high helium and metal content of stars in the Galactic Bulge. It is also argued that existing data are consistent with the bulk of stars in the Bulge being at least as old as galactic globular clusters.