Massive, wide binaries as tracers of massive star formation

Abstract

Massive stars can be found in wide (hundreds to thousands AU) binaries with other massive stars. We use $N$-body simulations to show that any bound cluster should always have approximately one massive wide binary: one will probably form if none are present initially; and probably only one will survive if more than one are present initially. Therefore any region that contains many massive wide binaries must have been composed of many individual subregions. Observations of Cyg OB2 show that the massive wide binary fraction is at least a half (38/74) which suggests that Cyg OB2 had at least 30 distinct massive star formation sites. This is further evidence that Cyg OB2 has always been a large, low-density association. That Cyg OB2 has a normal high-mass IMF for its total mass suggests that however massive stars form they 'randomly sample' the IMF (as the massive stars did not 'know' about each other).

arXiv comment8 pages, 6 figures, accepted for publication in MNRAS

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Cited by in corpus (6)

• OB associations and their origins
• A pilot survey of the binarity of Massive Young Stellar Objects with $K$ band adaptive optics
• A Search for In-Situ Field OB Star Formation in the Small Magellanic Cloud
• The velocity structure of Cygnus OB2
• A High Angular Resolution Survey of Massive Stars in Cygnus OB2: $JHK$ Adaptive Optics Results from the Gemini Near-InfraRed Imager
• Orbital Parameters and Binary Properties of 37 FGK stars in the Cores of Open Clusters NGC 2516 and NGC 2422