The Star Formation History in the Solar Neighborhood as Told by Massive White Dwarfs

摘要

White dwarfs (WDs) are the remnants of low- and intermediate-mass stars. Because of electron degeneracy, their evolution is just a simple gravothermal process of cooling. Recently, thanks to Gaia data, it has been possible to construct the luminosity function of massive (0.9≤M/M_⊙≤1.1) WDs in the solar neighborhood (d< 100 pc). Because the lifetime of their progenitors is very short, the birth times of both parents and daughters are very close and facilitate the reconstruction of an (effective) star formation rate. This rate started growing from zero during the early Galaxy and reached a maximum 6-7 Gyr ago. It declined and ~5 Gyr ago started to climb once more, reaching a maximum 2-3 Gyr ago; it has decreased since then. There are some traces of a recent star formation burst, but the method used here is not appropriate for recently born WDs.