A spectroscopic survey on the multiplicity of high-mass stars
Abstract
The formation of stars above about 20 M⊙ and their apparently high multiplicity remain heavily debated subjects in astrophysics. We have performed a vast high-resolution radial velocity spectroscopic survey of about 250 O- and 540 B-type stars in the southern Milky Way which indicates that the majority of stars (>82 per cent) with masses above 16 M⊙ form close binary systems while this fraction rapidly drops to 20 per cent for stars of 3 M⊙. The binary fractions of O-type stars among different environment classes are: clusters (72 ± 13 per cent), associations (73 ± 8 per cent), field (43 ± 13 per cent) and runaways (69 ± 11 per cent). The high frequency of close pairs with components of similar mass argues in favour of a multiplicity originating from the formation process rather than from a tidal capture in a dense cluster. The high binary frequency of runaway O stars that we found in our survey (69 per cent compared to 19-26 per cent in previous surveys) points to the importance of ejection from young star clusters and thus supports the competitive accretion scenario.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- August 2012
- DOI:
- 10.1111/j.1365-2966.2012.21317.x
- arXiv:
- arXiv:1205.5238
- Bibcode:
- 2012MNRAS.424.1925C
- Keywords:
-
- binaries: close;
- binaries: general;
- binaries: spectroscopic;
- stars: early-type;
- stars: formation;
- Astrophysics - Solar and Stellar Astrophysics
- E-Print:
- 6 pages, 4 figures, accepted by MNRAS