Massive stars in the Sagittarius Dwarf Irregular Galaxy

TL;DR

This study confirms the presence of massive stars in the low-metallicity SagDIG galaxy using spectroscopy, highlighting potential candidates as the most metal-poor massive stars in the Local Group, which are crucial for understanding early universe processes.

Contribution

First spectroscopic confirmation of massive stars in SagDIG, providing candidates for the most metal-poor massive stars in the Local Group.

Findings

Detected three OBA-type stars and one red supergiant candidate.

Potential discovery of the most metal-poor massive stars in the Local Group.

Supports SagDIG as an accessible laboratory for early universe studies.

Abstract

Low metallicity massive stars hold the key to interpret numerous processes in the past Universe including re-ionization, starburst galaxies, high-redshift supernovae and GRBs. The Sagittarius Dwarf Irregular Galaxy (SagDIG, 12+log(O/H)=7.37) represents an important landmark in the quest for analogues accessible with 10-m class telescopes. This paper presents low-resolution spectroscopy executed with the Gran Telescopio Canarias that confirms that SagDIG hosts massive stars. The observations unveiled three OBA-type stars and one red supergiant candidate. Pending confirmation from high-resolution follow-up studies, these could be the most metal-poor massive stars of the Local Group.