spectral peculiarities into a companion star which should have produced such material. The mass transfer episode is believed to be quite brief on an astronomical timescale. Prototypical barium stars include zeta Capricorni, HR 774, and HR 4474. The CH stars are Population II stars with similar evolutionary state, spectral peculiarities, and orbital statistics, and are believed to be the older, metal-poor analogs of the barium stars. References Star types Barium