THE LAMBDA-3984 FEATURE IN LATE-B SPECTROSCOPIC BINARIES

We report about a spectroscopic study aimed at searching the line Hg I I lambda 3984 in a sample of 28 spectroscopic binaries with primaries in the same temperature range as HgMn stars. One system, HD 75642, sho ws this line very prominently. In another system, HD 41040, Hg may be somewhat overabundant, while HD 87751 shows marginal Mn and P enhancem ent. The present study does not bring a definitive answer to the quest ion of the relation between binarity, slow rotation, and the appearanc e of HgMn anomalies in late B stars, possibly because other effects (l ike the influence of a magnetic held), which could not be taken into c onsideration, are important too. In the course of this study, 11 new d ouble-lined spectroscopic binaries were discovered, 10 of which were p reviously known as single-lined systems. Of particular interest among them are 4 stars that may have the Si or He weak peculiarities.