O and Fe abundance correlations and distributions inferred for the thick and thin disk

Abstract

A linear [Fe/H]-[O/H] relation is found for different stellar populations in the Galaxy (halo, thick disk, thin disk) from a data sample obtained in a recent investigation (Ramґırez et al. 2013). These correlations support previous results inferred from poorer samples: stars display a “main sequence” expressed as [Fe/H] = a[O/H] + b -+ Δb where the unit slope, a = 1, implies a constant [O/Fe] abundance ratio. Oxygen and iron empirical abundance distributions are then determined for different subsamples, which are well explained by the theoretical predictions of multistage closed-(box+reservoir) (MCBR) chemical evolution models taking into account the found correlations. The interpretation of these distributions in the framework of MCBR models gives us clues about inflow/outflow rates in these different Galactic regions and their corresponding evolution. Outflow rates for the thick and the thin disks are lower than the halo outflow rate. Besides that, the iron-to-oxygen yield ratio and the primary to not primary contribution ratio for the iron production are obtained from the data, resulting consistent with the SNII progenitor nucleosynthesis and with the iron production from SNIa supernova events.

Keywords

• galaxy: evolution
• galaxy: formation
• stars: evolution
• stars: formation