THE PURSUIT OF HEAVY-ELEMENTS IN THE HGMN-TYPE STAR CHI-LUPI - OBSERVATIONS WITH THE GHRS IN THE COSTAR ERA

Observations of the ultra-sharp-lined HgMn star chi Lupi made with the Goddard High Resolution Spectrograph after the Hubble Space Telescope First Servicing Mission display the effect of COSTAR corrective optic s upon the spectral resolution of several observing modes. The resolut ion is restored to levels expected in the absence of the telescope sph erical aberration for all observations made through the GHRS Large Sci ence Aperture (LSA). The Small Science Aperture (SSA) spectra are near ly identical in resolution to the pre-COSTAR values while benefiting f rom higher throughput. The line spread function for the LSA relative t o the SSA shows little wavelength dependence and reflects a Gaussian p rofile approximately 20%-30% broader than for SSA spectra. Absorption features containing components of As II and Bi II represent upper limi t enhancements of 2.9 and 2.1 dex for As II and Bi II, respectively, r elative to meteoritic abundance determinations.