Study of physical properties of spectroscopic binary stars

The main results of a study of a catalogue of physical parameters of 1041 spectroscopic binaries are presented. The distribution of spectroscopic binaries over all main parametersM1, a, e, M1/M2, P, and certain dependencies between some of them have been found.(1)It appears that among bright (mv≲3m–5m) stars withM≳1M⊙, about 40% are apparently spectroscopic binaries with comparable masses of components.(2)The majority of spectroscopic binaries with the ratio of the large semiaxis of the orbit to the radius of the primarya/R1≲20, have eccentricities close to zero. This is probably a consequence of the tidal circularization of orbits of close binaries by viscous friction.(3)The discovery of duplicity of double-line spectroscopic binaries is possible only if the semiamplitude of radial velocityK1 is almost 10 times higher than the semiamplitude of the radial velocity of a single-line spectroscopic binary of the same mass.(4)Double-line spectroscopic binaries witha/R⊙≲6(M1/M⊙)1/3,M1≈M2≳1.5M⊙ are almost almost absent, and the number of stars witha/R⊙≲6(M1/M⊙)1/3,M1≈1.5M⊙ is relatively low.(5)The distribution of unevolved SB stars over the large semiaxis may be described by the expression d(Nd/Nt)≈0.2 d loga for 6(M1/M⊙)1/3≲a/R⊙≲100.(6)The intial mass-function for primaries of spectroscopic binaries is the same Salpeter function dNd≈M1−2.35dM1 for 1≲M1/M⊙≲30.(7)It is possible to explain the observed ratio of the number of single-line spectroscopic binaries to the number of double-line binaries if one assumes that the average initial mass ratio is close to 1 and that the mass of the postmass-exchange remnant of the primary exceeds the theoretical one and/or that half of the angular momentum of the system is lost during mass-exchange.(8)The above-mentioned distributions ofM1 anda and assumptions on the mass of remnant and/or momentum loss also allow us to explain the observed shapes of dN/dM, dN/dq, and dN/da distributions after some selection effects are taken into account.