A deep near-infrared spectroscopic survey of the Scutum-Crux arm for Wolf-Rayet stars
Abstract
We present a New Technology Telescope/Son-of-Isaac spectroscopic survey of infrared selected Wolf-Rayet (WR) candidates in the Scutum-Crux spiral arm (298° ≤ l ≤ 340°, |b| ≤ 0.5°. We obtained near-IR spectra of 127 candidates, revealing 17 WR stars - a ∼13 per cent success rate - of which 16 are newly identified here. The majority of the new WR stars are classified as narrow-lined WN5-7 stars, with two broad-lined WN4-6 stars and three WC6-8 stars. The new stars, with distances estimated from previous absolute magnitude calibrations, have no obvious association with the Scutum-Crux arm. Refined near-infrared (YHJK) classification criteria based on over a hundred Galactic and Magellanic Cloud WR stars, providing diagnostics for hydrogen in WN stars, plus the identification of WO stars and intermediate WN/C stars. Finally, we find that only a quarter of WR stars in the survey region are associated with star clusters and/or H II regions, with similar statistics found for luminous blue variables (LBVs) in the Milky Way. The relative isolation of evolved massive stars is discussed, together with the significance of the co-location of LBVs and WR stars in young star clusters.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- January 2018
- DOI:
- 10.1093/mnras/stx2103
- arXiv:
- arXiv:1708.03582
- Bibcode:
- 2018MNRAS.473.2853R
- Keywords:
-
- stars: emission-line;
- Be;
- stars: evolution;
- stars: Wolf-Rayet;
- Galaxy: stellar content;
- infrared: stars;
- stars: Wolf-Rayet - Galaxy: stellar content;
- Astrophysics - Solar and Stellar Astrophysics;
- Astrophysics - Astrophysics of Galaxies
- E-Print:
- 19 pages, accepted for MNRAS, plus 13 pages of supplementary information including near-IR spectral classification of WR stars