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Elemental abundance analyses with coadded DAO spectrograms. I - The field horizontal-branch stars HD-64488, 109995 and 161817
It is possible to improve the quality of elemental-abundance analyses byusing higher-S/N data than has been the practice at high resolution. Theprocedures developed at the Dominion Astrophysical Observatory to coaddhigh-dispersion coude spectrograms are used with a minimum of 106.5-A/mm IIa-O spectrograms of each of three field hoorizontal-branch(FHB) A stars to increase the S/N of the photographic data over aconsiderable wavelength region. Fine analyses of the sharp-linedprototype FHB stars HD 109995 and 161817 show an internal consistencywhich justifies this effort. Their photospheric elemental abundances aresimilar to those of Population II globular cluster giants. As theirphotometric and spectrophotometric properties are similar to blue HBstars in such clusters, they are confirmed to be the brighter analogs ofsuch stars. HD 64488, which is photometrically andspectrophotometrically similar to the FHB stars, is found to bemetal-poor (Fe/H = -1) with much broader lines (v sin i = 147 km/s). Theimplications of the abundance anomalies of all three stars arediscussed.
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