THE ABUNDANCES OF PT, AU, AND HG IN THE CHEMICALLY PECULIAR HGMN-TYPESTARS KAPPA-CANCRI AND CHI-LUPI

Echelle mode spectra obtained with the Goddard High Resolution Spectro graph onboard the Hubble Space Telescope have been used to determine t he abundances of the heavy elements Pt, Au, and Hg in the chemically p eculiar HgMn-type stars kappa Cancri and chi Lupi. The abundances were determined by fitting observed line profiles with synthetically gener ated spectra and are found to be enhanced relative to solar system val ues by between three and five orders of magnitude in both stars. The H g isotope mixture in kappa Cancri is found to resemble the terrestrial mixture while that of chi Lupi is dominated by the heaviest isotope. As determined from multiple ionization states, the abundances place co nstraints upon theories attempting to explain the large surficial abun dances of heavy elements.