Vol. 521In section 1. Letters to the Editor19 October 2010

Chemical evolution of the Galactic bulge as traced by microlensed dwarf and subgiant stars. III. Detection of lithium in the metal-poor bulge dwarf MOA-2010-BLG-285S

by T. Bensby, M. Asplund, J. A. Johnson, S. Feltzing, J. Melendez, et al., A&A 521, L57 alt

Li is the only element heavier that H and He that is measurably produced in the Big Bang, and its primordial abundance is therefore of significant cosmological interest. The Li abundance in giant stars is susceptible to nuclear processing, and dwarf stars provide much cleaner measurements. They are, however, too faint to be observed at high spectral resolution at the distance of the Galactic bulge. The authors took advantage of the amplification of the light of bulge star MOA-2010-BLG-285S by a factor of 500 to obtain a high-quality spectrum. They find that its lithium abundance is similar to that of halo stars, suggesting that the Spite plateau is universal.