On the distribution of binary system mass ratios
Abstract
Mass ratios have been calculated for all binary systems in the Sixth Catalogue of the Orbital Elements Spectroscopic Binary Systems and the 1971 and 1973 supplements to it, and their distribution function is presented. The total sample is clearly bimodal, with peaks near mass ratios of 0.3 and 1.0, and the bimodality is preseved when only systems with known angles of orbital inclination are considered. It is also present in the subsample of unevolved systems, which suggests that there may be two populations of binaries formed in different ways. The distribution of mass ratios of the single-lined systems alone can be fitted satisfactorily with a hyperbola or parabola for analytic purposes. The power law fit adopted by previous workers is not satisfactory, and this analysis shows a greater preponderance of low-mass ratio systems than previously found. Between two and five percent of the single-line systems have mass ratios greater than one. Separating the binaries by spectral type does not reveal any striking differences, though the OB systems may be rather more strongly concentrated toward small mass ratios than the others, and systems with MK class I and II primaries may have a slight deficiency of low-mass ratios.
- Publication:
-
The Astronomical Journal
- Pub Date:
- September 1974
- DOI:
- 10.1086/111639
- Bibcode:
- 1974AJ.....79..967T