On the origin of binaries with twin components
A.A. Tokovinin 1,2
Received 17 January 2000 / Accepted 3 July 2000
The existence of a statistically significant excess of dwarf binaries with mass ratios from 0.95 to 1, as first noted by Lucy & Ricco (1979), is confirmed by modern data. Excess of such binaries, called twins, is found only for periods shorter than 40 days, and in the 2-30 days period range they constitute % of the total binary population. Twins must have been formed by a special mechanism. It cannot be a mass transfer in contact pre-main-sequence binaries, fission is also unlikely. As shown by Bate (2000), accretion onto a close binary shifts mass ratio towards 1, so twins may originate from binaries that became close while still surrounded by massive envelopes. Many twins are members of higher-multiplicity systems and/or clusters, which probably explains an early formation of a close binary by stellar dynamics.
Key words: stars: binaries: close stars: binaries: general stars: formation
© European Southern Observatory (ESO) 2000
Online publication: August 23, 2000