The Abundance Pattern of the A2.5V Star HD 176687 (ζ Sagitarii A) in A Triple System

Abstract The synthesis of high resolution high signal-to-noise ratio optical and IUE spectra of HD 176687 allows the determination of LTE abundances for carbon, nitrogen, oxygen, aluminum, silicon, strontium, yttrium and zirconium. Carbon, nitrogen, oxygen and silicon are found to be depleted by a factor of 0.50. Aluminum is overabundant by a factor of 2.0. Strontium is solar, yttium is overabundant by a factor of 6, zirconium has an upper limit of 1 solar. The comparison of the FUV spectral energy distribution of HD 176687 to those of standard stars confirms that its effective temperature must be about 8800 ± 200 K, slightly larger than that of the A3 V standard, α PsA.