Frequency of binaries, axial rotation and magnetism

Abstract

We discussed the correlation proposed by Abt and co-workers between average axial rotation of cluster members with respect to field stars of the same temperatures and the percentage of short-period spectroscopic binaries plus Ap and Bp with magnetic fields. This correlation was criticized by Crampton, Batten and co-workers and our discussion was done with a sample increased more then 200%. We obtained during the last 13 years almost 4000 spectrograms with a uniform dispersion of 40 Å/mm and suitable for radial velocity variables. We looked for periods among them and when we succeeded we derived preliminary orbital elements. With these results we concluded that the inverse correlation mentioned above is real with a confidence level of 1% or less.