The age of the Galactic thin disk from Th/Eu nucleocosmochronology: extended sample

Abstract

We report the determination of the age of the Galactic thin disk by means of Th/Eu nucleocosmochronology. This method is only weakly dependent on stellar evolutions models, therefore allowing an important verification of the most used dating techniques, which are the fitting of isochrones to the oldest Galactic open clusters, and the calculation of white dwarf cooling sequences. This work builds upon our previous determination (del Peloso et al. 2005a, 2005b), by including 7 new objects to the sample which was originally composed of 19 disk dwarfs/subgiants of F5 to G8 spectral types – a 37% extension. The obtained result, (8.8±1.7)Gyr, corroborates the most recent white dwarf ages determined via cooling sequence calculations, which indicate a low age ($\widetilde{<}10~\mbox{Gyr}$) for the disk.