Duplicity Among Solar-Type Stars

From a new study of 113 F8-G1 IV or V primaries in an apparent-magnitude limited sample, measured with a CCD for about 20 radial velocities of accuracy 0.2-0.5 km s−1 each, we collected data for 28 binary orbits and 39 visual systems. We again found a flat distribution (or slightly decreasing toward lower masses) of secondary masses, unlike the Salpeter distribution for B2-B5 stars. But we find that the different distributions for these field stars and for open clusters of various ages can all be explained by a capture mechanism of binary formation.