Massive binaries in high-mass star-forming regions: A multi-epoch radial velocity survey of embedded O-stars

Abstract

We present the first multi-epoch radial velocity study of embedded young massive stars using near-infrared spectra obtained with ISAAC mounted at the ESO Very Large Telescope, with the aim to detect massive binaries. Our 16 targets are located in high-mass star-forming regions and many of them are associated to known ultracompact HI I regions, whose young age ensures that dynamic evolution of the clusters did not influence the intrinsic binarity rate. We identify two stars with about 90 km/s velocity differences between two epochs proving the presence of close massive binaries. The fact that 2 out of the 16 observed stars are binary systems suggests that at least 20% of the young massive stars are formed in close multiple systems, but may also be consistent with most if not all young massive stars being binaries. In addition, we show that the radial velocity dispersion of the full sample is about 35 km/s, significantly larger than our estimated uncertainty (25 km/s). This finding is consistent with similar measurements of the young massive cluster 30 Dor which might have a high intrinsic binary rate. Furthermore, we argue that virial cluster masses derived from the radial velocity dispersion of young massive stars may intrinsically overestimate the cluster mass due to the presence of binaries.

To appear in the Astrophysical Journal (January 10, 2007, v654n 2 issue)

Cited by in corpus (13)

• The influence of multiple stars on the high-mass stellar initial mass function and age-dating of young massive star clusters
• The effect of binaries on the dynamical mass determination of star clusters
• A dearth of short-period massive binaries in the young massive star forming region M17: Evidence for a large orbital separation at birth?
• A pilot survey of the binarity of Massive Young Stellar Objects with $K$ band adaptive optics
• A relation between the radial velocity dispersion of young clusters and their age: Evidence for hardening as the formation scenario of massive close binaries
• Kinematics and stability of high-mass protostellar disk candidates at sub-arcsecond resolution -- Insights from the IRAM NOEMA large program CORE
• Effect of binarity in star cluster dynamical mass determination
• The first interferometric survey in the K-band of massive YSOs. On the hot dust, ionised gas, and binarity at au scales
• Near-infrared spectroscopy of the massive stellar population of W51: evidence for multi-seeded star formation
• GRAVITY spectro-interferometric study of the massive multiple stellar system HD 93 206 A
• The onset of stellar multiplicity in massive star formation: A search for low-mass companions of massive young stellar objects with $L^{\prime }$-band adaptive optics imaging
• Infrared study of the southern Galactic star forming regions associated with IRAS 10049-5657 and IRAS 10031-5632
• Surveys of clumps, cores, and condensations in Cygnus-X: Searching for Keplerian disks on the scale of 500 au