The white dwarf companion of the barium star ZET Cap.

Abstract

It is shown that the barium star Zeta Cap has a white dwarf companion with a mass of approximately 1.0 solar masses and an effective temperature of 23,000 K. Strong emission lines and very deep reversals in the Mg II emission line cores indicate circumstellar gas which may be due to mass transfer in the system. The Ba star HD 65699 also shows the very deep central reversals in very strong Mg II emission cores. The weak spectra of the barium stars Zeta Cyg, HD 65699, and HD 116713 probably show excessive UV radiation also, but further studies are necessary.