Spectroscopic binaries in the Orion OB1 association

A radial velocity study of the brighter members of the Ori OB2 association is reported. The radial velocity variables, new preliminary orbital elements for six spectroscopic binaries, and the projected axial rotation in stars for which the orbital elements are lacking are reported. The correlation between the proportion of binaries and the average axial rotation for the subgroups of the association is discussed. It is found that the Orion main-sequence members rotate at almost the same rate as field stars of the same types. The average radial velocity for the whole association is 23 km/s. The percentage of spectroscopic binaries with periods shorter than 100 days plus the magnetic Ap-Bp among the main-sequence members of the association is 32 percent.