A Near-Infrared Survey of the Inner Galactic Plane for Wolf-Rayet Stars I. Methods and First Results: 41 New WR Stars

TL;DR

This paper presents a new infrared survey of the Galactic plane that successfully identified 41 new Wolf-Rayet stars, including some among the most distant in our Galaxy, using advanced imaging and spectroscopic techniques.

Contribution

It introduces a novel infrared imaging method for detecting Wolf-Rayet stars obscured by dust, leading to the discovery of 41 new WR stars and improved understanding of their distribution.

Findings

Discovered 41 new Wolf-Rayet stars in the Galactic plane.

The new WR stars follow the spiral arm distribution of known WR stars.

Some of the new WR stars are among the most distant in the Galaxy.

Abstract

The discovery of new Wolf-Rayet (WR) stars in our Galaxy via large-scale narrowband optical surveys has been severely limited by dust extinction. Recent improvements in infrared technology have made narrowband-broadband imaging surveys viable again. We report a new J, K and narrow-band imaging survey of 300 square degrees of the plane of the Galaxy, spanning 150 degrees in Galactic longitude and reaching 1 degree above and below the Galactic plane. The survey has a useful limiting magnitude of K = 15 over most of the observed Galactic plane, and K = 14 within a few degrees of the Galactic center. Thousands of emission line candidates have been detected. In spectrographic follow-ups of 173 WR star candidates we have discovered 41 new WR stars, 15 of type WN and 26 of type WC. Star subtype assignments have been confirmed with K band spectra, and distances approximated using the method of spectroscopic parallax. A few of the new WR stars are amongst the most distant known in our Galaxy. The distribution of these new WR stars is seen to follow that of previously known WR stars along the spiral arms of the Galaxy. Tentative radial velocities were also measured for most of the new WR stars.