A Near-Infrared Survey of the Inner Galactic Plane for Wolf-Rayet Stars II. Going Fainter: 71 More New WR Stars

TL;DR

This study extends a near-infrared survey of the Galactic plane, discovering 71 new Wolf-Rayet stars, including some among the most distant in our Galaxy, thereby enhancing understanding of massive star distribution.

Contribution

The paper reports the discovery of 71 new Wolf-Rayet stars using an improved infrared survey and analysis pipeline, expanding the known population and spatial distribution of these stars.

Findings

Discovered 71 new Wolf-Rayet stars, including 17 WN and 54 WC types.

Survey success rate of 57% for identifying Wolf-Rayet candidates.

New WR stars help trace the Galaxy's spiral arms and distant regions.

Abstract

We are continuing a J, K and narrow-band imaging survey of 300 square degrees of the plane of the Galaxy, searching for new Wolf-Rayet stars. Our survey spans 150 degrees in Galactic longitude and reaches 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 (due to severe crowding) within a few degrees of the Galactic center. Thousands of emission line candidates have been detected. In spectrographic follow-ups of 146 relatively bright WR star candidates we have re-examined 11 previously known WC and WN stars and discovered 71 new WR stars, 17 of type WN and 54 of type WC. Our latest image analysis pipeline now picks out WR stars with a 57% success rate. Star subtype assignments have been confirmed with K band spectra, and distances approximated using the method of spectroscopic parallax. Some of the new WR stars are amongst the most distant known in our Galaxy. The distribution of these new WR stars is beginning to trace the locations of massive stars along the distant spiral arms of the Milky Way.