Discovery of a Wolf-Rayet Star Through Detection of its Photometric Variability

TL;DR

This paper reports the serendipitous discovery of a heavily reddened Wolf-Rayet star, WR142b, identified through photometric variability and confirmed by spectroscopy as a nitrogen-rich WN6 type with no hydrogen or hot companion.

Contribution

First detection of WR142b through photometric variability leading to spectroscopic confirmation of a new Wolf-Rayet star with detailed spectral analysis.

Findings

WR142b is a nitrogen-rich WN6 Wolf-Rayet star.

No hydrogen or hot companion detected in WR142b.

Significant dust extinction implies the star could be visible without dust.

Abstract

We report the serendipitous discovery of a heavily reddened Wolf-Rayet star that we name WR142b. While photometrically monitoring a cataclysmic variable, we detected weak variability in a nearby field star. Low-resolution spectroscopy revealed a strong emission line at 7100 Ang., suggesting an unusual object and prompting further study. A spectrum taken with the Hobby-Eberly Telescope confirms strong HeII emission and a NIV 7112 Ang. line consistent with a nitrogen-rich Wolf-Rayet star of spectral class WN6. Analysis of the HeII line strengths reveals no detectable hydrogen in WR142b. A blue-sensitive spectrum obtained with the Large Binocular Telescope shows no evidence for a hot companion star. The continuum shape and emission line ratios imply a reddening of E(B-V)=2.2 to 2.5 mag. If not for the dust extinction, this new Wolf-Rayet star could be visible to the naked eye.