The Binary Frequency and Origin of the OB Runaway Stars
Abstract
A radial velocity survey of the bright northern OB runaway stars has been undertaken to determine the frequency of binary stars in this high-velocity group. A total of 634 high-dispersion spectrograms of 36 proposed runaway stars were obtained over a two year period. Approximately half of the stars are velocity-variable; these include seven spectroscopic binaries, one possible beta-Cephei variable, and 10 stars with emission lines in their spectra. The latter group contains seven of the eight Be stars observed and three luminous O stars, and it is argued that their variability is caused by nonradial pulsation. Fifteen of the program stars have a peculiar radial velocity greater than 30 km/s; five others are probable runaways on the basis of distance from the galactic plane and proper motion. Only two of the confirmed and probable runaways, HD 3950 and HD 198846 (Y Cyg), are binaries, and both are double-lines systems. New orbital elements are presented for HD 3950 and the five new binary systems found among the low-velocity stars. The statisical methods used to assess velocity variability and periodic signals are described in detail. The higher fractional abundance of runaways among more massive stars, their binary frequency, and the properties of the runaway binaries suggest that they obtained their high velocities through single-binary, binary-binary, or n-body close encounters during the early dynamical evolution of associations.
- Publication:
-
The Astrophysical Journal Supplement Series
- Pub Date:
- June 1986
- DOI:
- 10.1086/191118
- Bibcode:
- 1986ApJS...61..419G
- Keywords:
-
- B Stars;
- Binary Stars;
- Early Stars;
- O Stars;
- Radial Velocity;
- Analysis Of Variance;
- High Dispersion Spectrographs;
- Orbital Elements;
- Statistical Tests;
- Velocity Measurement;
- Astrophysics;
- STARS: BINARIES;
- STARS: EARLY-TYPE;
- STARS: STELLAR DYNAMICS