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

Dániel Apai, Arjan Bik, Lex Kaper, Thomas Henning, Hans Zinnecker

Research output: Contribution to journalArticlepeer-review

25 Scopus citations


We present the first multiepoch 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 of detecting massive binaries. Our 16 targets are located in high-mass star-forming regions, and many of them are associated with known ultracompact H II 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-1 velocity differences between two epochs, proving the presence of close massive binaries. The fact that two 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-1, significantly larger than our estimated uncertainty (25 km s-1). 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.

Original languageEnglish (US)
Pages (from-to)484-491
Number of pages8
JournalAstrophysical Journal
Issue number1 I
StatePublished - Jan 20 2007


  • Binaries: close
  • Binaries: spectroscopic
  • Infrared: stars
  • Stars: early-type
  • Stars: formation

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


Dive into the research topics of 'Massive binaries in high-mass star-forming regions: A multiepoch radial velocity survey of embedded O stars'. Together they form a unique fingerprint.

Cite this