# Low-metallicity (sub-SMC) massive stars

## TL;DR

This paper reviews recent advances in studying massive stars in low-metallicity environments, leveraging new spectroscopic data from large telescopes to test stellar evolution models relevant to the early universe.

## Contribution

It summarizes current knowledge and recent observational progress in understanding massive stars at metallicities below that of the SMC, highlighting new data and research directions.

## Key findings

- Improved spectroscopic data from large telescopes enables better understanding of low-metallicity massive stars.
- Observations are used to test and refine stellar evolutionary models in metal-poor regimes.
- Research informs models applicable to the high-redshift, metal-poor universe.

## Abstract

The double distance and metallicity frontier marked by the SMC has been finally broken with the aid of powerful multi-object spectrographs installed at 8-10m class telescopes. VLT, GTC and Keck have enabled studies of massive stars in dwarf irregular galaxies of the Local Group with poorer metal content than the SMC. The community is working to test the predictions of evolutionary models in the low-metallicity regime, set the new standard for the metal-poor high-redshift Universe, and test the extrapolation of the physics of massive stars to environments of decreasing metallicity. In this paper, we review current knowledge on this topic.