barium star

A barium star is a giant star of spectral type G2 to K4 whose spectrum contains unusually strong absorption lines of barium (notably the 4554 Å line) and of some other heavy elements such as strontium. Also known as heavy-metal stars or Ba II stars, barium stars are thought to have been contaminated with by-products of nuclear fusion by companions that have already far evolved and are now white dwarfs. An example is Altarf (Beta Cancri).