barium stars


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barium stars

(bair -ee-ŭm) A class of stars, usually G or K giants, that show anomalous enhancements of barium, strontium, and other s-process elements in their spectra. Observations show that barium stars are exclusively found in binary star systems, with periods between a few months and a few years, in which the companion is a white dwarf. Because the barium-rich star is usually not sufficiently evolved to have produced the chemical anomalies in its interior, it is now generally believed that it acquired material enriched in s-process elements by mass transfer from the companion, when the latter was an asymptotic giant (presumably an S star). See also CH stars.