Search for LBV Candidates in the M33 Galaxy

TL;DR

This study identifies 210 LBV candidates in M33 using photometric and emission criteria, finding significant variability and consistency with previous emission-line object lists, advancing the understanding of massive star populations.

Contribution

The paper introduces a new catalog of LBV candidates in M33 based on H-alpha imaging and photometry, including reddened candidates, with validation against known variables.

Findings

29% of candidates are photometrically variable

Good agreement with previous emission-line object lists

Identification of reddened LBV candidates

Abstract

A total of 185 luminous blue variable (LBV) candidates with V < 18.5 and B-V < 0.35 are selected based on the photometrical Survey of Local Group Galaxies made by P. Massey et al. 2006. The candidates were selected using aperture photometry of H-alpha images. The primary selection criterion is that the prospective candidate should be a blue star with H-aplha emission. In order not to miss appreciably reddened LBV candidates, we compose an additional list of 25 presumably reddened (0.35 < B-V < 1.2, V < 18.5) emission star candidates. A comparison with the list of known variables in the M33 galaxy showed 29% of our selected candidates to be photometrically variable. We also find our list to agree well with the lists of emission-line objects obtained in earlier papers using different methods.