12 New Galactic Wolf-Rayet Stars Identified via 2MASS+Spitzer/GLIMPSE

TL;DR

This study identifies 12 new obscured Wolf-Rayet stars in the Milky Way using infrared color excesses from 2MASS and Spitzer/GLIMPSE data, expanding the catalog of known stars of this type.

Contribution

It introduces a new infrared color-based method for discovering Wolf-Rayet stars and confirms 12 new stars, including a potential dust-producing binary, enhancing understanding of their distribution.

Findings

Confirmed 12 new Wolf-Rayet stars in the Galaxy.

Discovered a possible dust-producing WC9d+OBI binary.

Most stars are likely runaways or formed in isolation.

Abstract

We report new results from our effort to identify obscured Wolf-Rayet stars in the Galaxy. Candidates were selected by their near-infrared (2MASS) and mid-infrared (Spitzer/GLIMPSE) color excesses, which are consistent with free-free emission from ionized stellar winds and thermal excess from hot dust. We have confirmed 12 new Wolf-Rayet stars in the Galactic disk, including 9 of the nitrogen subtype (WN), and 3 of the carbon subtype (WC); this raises the total number of Wolf-Rayet stars discovered with our approach to 27. We classify one of the new stars as a possible dust-producing WC9d+OBI colliding-wind binary, as evidenced by an infrared excess resembling that of known WC9d stars, the detection of OBI features superimposed on the WC9 spectrum, and hard X-ray emission detected by XMM-Newton. A WC8 star in our sample appears to be a member of the stellar cluster Danks 1, in contrast to the rest of the confirmed Wolf-Rayet stars that generally do not appear to reside within dense stellar clusters. Either the majority of the stars are runaways from clusters, or they formed in relative isolation. We briefly discuss prospects for the expansion and improvement of the search for Wolf-Rayet stars throughout the Milky Way Galaxy.