Are the majority of Sun-like stars single?

A. P. Whitworth, O. Lomax

(Submitted on 13 Feb 2015)

It has recently been suggested that, in the field, ∼56% of Sun-like stars (0.8M??M??1.2M?) are single. We argue here that this suggestion may be incorrect, since it appears to be based on the multiplicity frequency of systems with Sun-like primaries, and therefore takes no account of Sun-like stars that are secondary (or higher-order) components in multiple systems. When these components are included in the reckoning, it seems likely that only ∼46% of Sun-like stars are single.

This estimate is based on a model in which the system mass function has the form proposed by Chabrier, with a power-law Salpeter extension to high masses; there is a flat distribution of mass ratios; and the probability that a system of mass M is a binary is 0.50+0.46log10(M/M?) for 0.08M?≤M≤12.5M?, 0 for M<0.08M?, and 1 for M>12.5M?. The constants in this last relation are chosen so that the model also reproduces the observed variation of multiplicity frequency with primary mass.

However, the more qualitative conclusion, that a minority of Sun-like stars are single, holds up for virtually all reasonable values of the model parameters. Parenthetically, it is still likely that the majority of {\it all} stars in the field are single, but that is because most M Dwarfs probably are single.

Comments: 6 pages. Accepted by MNRAS

Subjects: Solar and Stellar Astrophysics (astro-ph.SR)

Cite as: arXiv:1502.04018 [astro-ph.SR] (or arXiv:1502.04018v1 [astro-ph.SR] for this version)

Submission history

From: Oliver Lomax  

[v1] Fri, 13 Feb 2015 15:00:27 GMT (2565kb,D)

http://arxiv.org/abs/1502.04018

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