G. R. Solivella

Spectroscopic binaries in the open cluster Collinder 228

A radial velocity study of the members of the open cluster Collinder 228 is presented. For a total of 55 stars in the field of the cluster, an average of 10 spectra per star, is obtained and used to derive preliminary orbital elements for six new spectroscopic binaries. With the same observational material, projected axial rotation velocities are derived for stars later than O9 on the main sequence. A statistical discussion based on the above data indicated that the minimum proportion of binaries among the main sequence members of Collinder 228 in the spectral range O9-B3, is 31 percent while the average projected axial rotation of the cluster members with respect to the average rotation for field stars of the same types is 0.89 + or - 0.12. Several early-type SB2 systems of potential astrophysical interest are pointed out. 20 refs.

Radial velocities in the open cluster Trumpler 14

In this paper we present radial velocity measurements of probable members of Trumpler 14, a very young open cluster associated with the Carina Nebula. We have found 4 double-line spectroscopic binaries and 2 single-line spectroscopic binaries. We have succeeded in deriving orbital elements for the SB1s. All the binaries are of potential astrophysical interest and are worth further observational efforts.