Abundances of massive stars: some recent developments

TL;DR

Recent developments in the study of massive star abundances reveal lower-than-expected metal levels in nearby OB stars and challenge current models including rotation in explaining CNO element properties.

Contribution

The paper discusses new abundance data for early-type stars and highlights discrepancies with existing evolutionary models.

Findings

Nearby OB stars show sub-solar metal abundances.

Current models including rotation fail to explain observed CNO properties.

Increased abundance data enhances understanding of stellar and galactic evolution.

Abstract

Thanks to their usefulness in various fields of astrophysics (e.g. mixing processes in stars, chemical evolution of galaxies), the last few years have witnessed a large increase in the amount of abundance data for early-type stars. Two intriguing results emerging since the last reviews on this topic will be discussed: (a) nearby OB stars exhibit metal abundances generally lower than the solar/meteoritic estimates; (b) evolutionary models of single objects including rotation are largely unsuccessful in explaining the CNO properties of stars in the Galaxy and in the Magellanic clouds.