HII Regions And the Protosolar Helium, Carbon, and Oxygen Abundances in the Context of Galactic Chemical Evolution

TL;DR

This paper develops chemical evolution models of the Galactic disk incorporating Z-dependent yields, successfully fitting observed abundance gradients, protosolar data, and extragalactic HII region relations, thereby enhancing understanding of galactic chemical history.

Contribution

It introduces a model with Z-dependent yields and moderate mass loss rates that accurately reproduces multiple observed abundance patterns in the Galaxy and beyond.

Findings

The model fits C/H and C/O gradients in the Galactic disk.

It aligns with protosolar and stellar abundance data.

It explains the origin of the Sun's position and star formation in the inner disk.

Abstract

We present chemical evolution models of the Galactic disk with different Z-dependent yields. We find that a moderate mass loss rate for massive stars of solar metallicity produces an excellent fit to the observed C/H and C/O gradients of the Galactic disk. The best model also fits: the H, He, C, and O abundances derived from recombination lines of M17, the protosolar abundances,and the C/O-O/H, C/Fe-Fe/H, and O/Fe-Fe/H relations derived from solar vicinity stars. The agreement of the model with the protosolar abundances implies that the Sun originated at a galactocentric distance similar to the one it has. Our model for $r=3$ kpc implies that a fraction of the stars in the direction of the bulge formed in the inner disc. We obtain a good agreement between our model and the C/O versus O/H relationship derived from extragalactic H~{\sc ii} regions in spiral galaxies.