THE BINARY NATURE OF THE SUBGIANT CH STARS

Repeated radial velocities have been measured for a sample of ten subg iant CH (sgCH) stars over a period of similar to 15 years. Long-term v elocity variations are exhibited by all but one star, and spectroscopi c orbits have been calculated for six of them. The periods are long, r anging from 876 to 4144 days. The distribution of eccentricities and m ass functions for sgCH star orbits are similar to those for giant bari um and CH stars, exhibiting significant orbital dissipation relative t o normal late-type binaries. It is concluded that all sgCH stars are b inaries, and like the barium and CH stars, they have had mass transfer red from a former asymptotic giant-branch star.