A Spectroscopic Survey of Massive Stars in M31 and M33

TL;DR

This spectroscopic survey of 1895 stars in M31 and M33 provides extensive classifications, identifies new luminous blue variables and Wolf-Rayet stars, and enhances existing catalogs with improved data, significantly advancing our understanding of massive stars in these galaxies.

Contribution

The study offers the first large-scale spectroscopic classification of stars in M31 and M33, discovering new massive star candidates and updating stellar catalogs with precise data.

Findings

Identified 1496 stars for the first time through spectroscopy.

Discovered 9 new candidate Luminous Blue Variables.

Found a previously unrecognized Wolf-Rayet star.

Abstract

We describe our spectroscopic follow-up to the Local Group Galaxy Survey (LGGS) photometry of M31 and M33. We have obtained new spectroscopy of 1895 stars, allowing us to classify 1496 of them for the first time. Our study has identified many foreground stars, and established membership for hundreds of early- and mid-type supergiants. We have also found 9 new candidate Luminous Blue Variables and a previously unrecognized Wolf-Rayet star. We republish the LGGS M31 and M33 catalogs with improved coordinates and including spectroscopy from the literature and our new results. The spectroscopy in this paper is responsible for the vast majority of the stellar classifications in these two nearby spiral neighbors. The most luminous (and hence massive) of the stars in our sample are early-type B supergiants, as expected; the more massive O stars will be fainter visually, and thus mostly remain unobserved so far. The majority of the unevolved stars in our sample are in the 20-40Mo range.