A CORAVEL RADIAL-VELOCITY MONITORING OF GIANT BA AND S STARS - SPECTROSCOPIC ORBITS AND INTRINSIC VARIATIONS - I

With the aim of deriving the binary frequency among Ba and S stars, 56 new spectroscopic orbits (46 and 10, respectively) have been derived for these chemically-peculiar red giants monitored with the CORAVEL sp ectrometers. These orbits are presented in this paper (38 orbits) and in a companion paper (Udry et al. 1998, Paper II; 18 orbits). The resu lts for 12 additional long-period binary stars (6 and 6, respectively) , for which only minimum periods (generally exceeding 10y) can be deri ved, are also presented here (10) and in Paper II (2). The global anal ysis of this material, with a few supplementary orbits from the litera ture, is presented in Jorissen et al. (1998). For the subsample of Mir a S, SC and (Tc-poor) C stars showing intrinsic radial-velocity variat ions due to atmospheric phenomena, orbital solutions (when available) have been retained if the velocity and photometric periods are differe nt (3 stars). However, it is emphasized that these orbit determination s are still tentative. Three stars have been found with radial-velocit y variations synchronous with the light variations. Pseudo-orbital sol utions have been derived for those stars. In the case of RZ Peg, a lin e-doubling phenomenon is observed near maximum light, and probably ref lects the shock wave propagating through the photosphere.