1538-3873/87/518/513
ABSTRACT
The isotopic shift of the Hg ii 3984 line is examined in the spectra of a number of strong mercury-manganese stars; the shift cannot be explained by line blending with lines of other elements in these stars, but represents real isotopic variations. An astrophysical log gf value of -1.8 is derived for x3984, based on the Hg i x4358 line strength in L CrB and HR 1800. Elemental and (in some cases) isotopic abundances of Hg are derived using a spectrum synthesis technique; overabundances of up to 5.4 dex over the solar system mercury abundance are found; the maximum overabundances may be temperature dependent. Key words: peculiar stars - stellar abundances.