A red-giant star of spectral type G or K in which heavier elements such as barium appear in the spectrum with unusually high abundance; also known as a Ba II star or a heavy-metal star. Barium stars are similar to CH stars, but are more metal-rich and have insufficient carbon to be considered as carbon stars. About 1% of G and K giants are barium stars. It seems probable that all barium stars are in binary systems with white-dwarf companions and long orbital periods (hundreds of days). Barium stars may therefore be the result of accretion of part of the matter ejected by an initially more massive companion when it was in a red-giant phase before becoming a white dwarf.
Subjects: Astronomy and Astrophysics.