Search and Study of the Brightest Stars in the Galaxy IC 342

TL;DR

This study identifies and classifies bright massive stars in galaxy IC 342 using archival images and spectral observations, discovering various stellar types including supergiants, Wolf-Rayet stars, and potential LBV candidates.

Contribution

It provides the first spectral classification and identification of diverse massive star types in IC 342, expanding understanding of stellar populations in external galaxies.

Findings

12 objects are single supergiants or unresolved clusters.

7 objects show Wolf-Rayet star features.

2 objects are potential LBV candidates.

Abstract

We have selected candidate massive stars in the galaxy IC 342 based on archival images from the Hubble Space Telescope and images from the 2 m telescope at the Natioal Astronomical Observatory Rozhen, Bulgaria. Spectral observations of 24 out of 27 selected stars are carried out with the 6 m BTA telescope at the SAO RAS and with the 3.5 m Apache Point Observatory telescope (USA) as part of the program for searching bright massive stars in galaxies outside the Local Group. Our analysis reveals that 12 objects have spectra lacking prominent features, except for the emission lines of the surrounding nebulae and are identified as single supergiants of classes O9 to F5 or spatially unresolved young compact clusters. One source with an absorption spectrum probably belongs to our Galaxy. The spectra of seven other objects show features typical of Wolf-Rayet stars or compact clusters containing Wolf-Rayet stars. Another source is a compact supernova remnant. Two other objects are tentatively classified as cold LBV candidates, and one object is classified as a B[e]-supergiant candidate.