Insights into the formation of barium and Tc-poor S stars from an   extended sample of orbital elements
  The set of orbital elements available for chemically-peculiar red giant (PRG) stars has been considerably enlarged thanks to a decade-long CORAVEL radial-velocity monitoring of about 70 barium stars and 50 S stars. This paper presents a detailed analysis of the complete set of orbital parameters available for PRG stars; the individual data are given in three companion papers. The main results are as follows: (i) The similarity between the orbital parameters of Tc-poor S stars and barium stars confirms that Tc-poor S stars are the cooler analogs of barium stars; (ii) The eccentricity -- period diagram of PRG stars clearly bears the signature of dissipative processes associated with mass transfer; (iii) The mass function distribution is compatible with the unseen companion being a white dwarf (WD); (iv) Assuming that the WD companion has a mass in the range 0.60+-0.04 Msun, the masses of mild and strong barium stars amount to 1.9+-0.2 and 1.5+-0.2 Msun, respectively; (v) Mild barium stars are not restricted to long-period systems; the difference between mild and strong barium stars is mainly one of galactic population rather than of orbital separation, in agreement with their respective kinematical properties; (vi) Binarity is probably not a sufficient condition to produce a PRG star, and a metallicity lower than solar seems to be required as well. 
A. Jorissen (1), S. Van Eck (1), M. Mayor (2), S. Udry (2) ((1)   Universite Libre de Bruxelles, Belgium, (2) Observatoire d...