Local (thick-disc) white dwarfs and the Galactic mass budget

Abstract

The stars of the solar neighbourhood essentially originate from two stellar populations: Population I (the thin disc) and Population II (the thick disc). Recently, we completed an unbiased sample of long-lived solar-type stars and demonstrated that the local normalization of the thick disc versus thin disc is about 20 per cent. In this second paper, we present the observational evidence that at least this percentage is also met in the realm of their degenerate counterparts and may even be as high as one-third. Along with the results from the solar-type stars, this is a direct confirmation of the thick disc being the massive and dark baryonic population of the Milky Way. © 2011 The Authors Monthly Notices of the Royal Astronomical Society © 2011 RAS.