The age of the Galactic thin disk from Th/Eu nucleocosmochronology II. Chronological analysis

E. F. del Peloso; L. da Silva; L. I. Arany-Prado

doi:10.1051/0004-6361:20042438

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The age of the Galactic thin disk from Th/Eu nucleocosmochronology II. Chronological analysis

E. F. del Peloso·L. da Silva·L. I. Arany-Prado

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Abstract

The purpose of this work is to resume investigation of Galactic thin disk dating using nucleocosmochronology with Th/Eu stellar abundance ratios, a theme absent from the literature since 1990. [Th/Eu] abundance ratios for a sample of 20 disk dwarfs/subgiants of F5 to G8 spectral type with -0.8 <= [Fe/H] <= +0.3, determined in the first paper of this series, were adopted for this analysis. We developed a Galactic chemical evolution model that includes the effect of refuses, which are composed of stellar remnants (white dwarfs, neutron stars and black holes) and low-mass stellar formation residues (terrestrial planets, comets, etc.), contributing to a better fit to observational constraints. Two Galactic disk ages were estimated, by comparing literature data on Th/Eu production and solar abundance ratios to the model ((8.7 +5.8-4.1) Gyr), and by comparing [Th/Eu] vs. [Fe/H] curves from the model to our stellar abundance ratio data ((8.2 +/- 1.9) Gyr), yielding the final, average value (8.3 +/- 1.8) Gyr. This is the first Galactic disk age determined via Th/Eu nucleocosmochronology, and corroborates the most recent white dwarf ages determined via cooling sequence calculations, which indicate a low age (<~ 10 Gyr) for the disk.

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E. F. del Peloso, L. da Silva, L. I. Arany-Prado. 2005-02-21. The age of the Galactic thin disk from Th/Eu nucleocosmochronology II. Chronological analysis. https://doi.org/10.1051/0004-6361%3A20042438

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