A spectroscopic investigation of early-type stars in the young open cluster Westerlund 2
Abstract
Context. The distance of the very young open cluster
Aims: We attempt a joint analysis of spectroscopic and photometric data of eclipsing binaries in the cluster to constrain its distance.
Methods: A sample of 15 stars, including three eclipsing binaries (
Results: The analysis of the three eclipsing binaries clearly supports the larger values of the distance, around 8 kpc, and rules out values of about 2.4 - 2.8 kpc that have been suggested in the literature. Furthermore, our spectroscopic monitoring reveals no clear signature of binarity with periods shorter than 50 days in either the WN6ha star
Conclusions: The distance of Westerlund 2 is confirmed to be around 8 kpc as previously suggested based on the spectrophotometry of its population of O-type stars and the analysis of the light curve of WR 20a. Our results suggest that short-period binary systems are not likely to be common, at least not among the population of O-type stars in the cluster.
- Publication:
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Astronomy and Astrophysics
- Pub Date:
- November 2011
- DOI:
- 10.1051/0004-6361/201117000
- arXiv:
- arXiv:1109.1086
- Bibcode:
- 2011A&A...535A..40R
- Keywords:
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- binaries: eclipsing;
- stars: early-type;
- open clusters and associations: individual: Westerlund 2;
- Sun: fundamental parameters;
- stars: individual: WR 20b;
- stars: individual: Westerlund 2 MSP 18;
- Astrophysics - Solar and Stellar Astrophysics
- E-Print:
- Accepted for publication in Astronomy &