Age-resolved chemistry of red giants in the solar neighbourhood
  In the age of high-resolution spectroscopic stellar surveys of the Milky Way,
the number of stars with detailed abundances of multiple elements is rapidly
increasing. These elemental abundances are directly influenced by the
evolutionary history of the Galaxy, but this can be difficult to interpret
without an absolute timeline of the abundance enrichment. We present
age-abundance trends for [M/H], [{\alpha}/M], and 17 individual elements using
a sample of 721 solar neighbourhood Hipparcos red giant stars observed by
APOGEE. These age trends are determined through a Bayesian hierarchical
modelling method presented by Feuillet et al. (2016). We confirm that the
[{\alpha}/M]- age relation in the solar neighbourhood is steep and relatively
narrow (0.20 dex age dispersion), as are the [O/M]- and [Mg/M]-age relations.
The age trend of [C/N] is steep and smooth, consistent with stellar evolution.
The [M/H]-age relation has a mean age dispersion of 0.28 dex and a complex
overall structure. The oldest stars in our sample are those with the lowest and
highest metallicities, while the youngest stars are those with solar
metallicity. These results provide strong constraints on theoretical models of
Galactic chemical evolution (GCE). We compare them to the predictions of
one-zone GCE mod- els and multi-zone mixtures, both analytic and numerical.
These comparisons support the hypothesis that the solar neighbourhood is
composed of stars born at a range of Galactocentric radii, and that the most
metal-rich stars likely migrated from a region with earlier and more rapid star
formation such as the inner Galaxy.
