Determination of the Abundance of Mercury from the Hg ii Line at 5677.10 Å in Late B-type Stars. IV. HD 149121 (28 Her) and HD 178065

Abstract

The weak line of Hg ii located at 5677.10 Å is used to measure the mercury abundance in two HgMn stars, HD 149121 (28 Her) and HD 178065. This line is detected at 3σ above the noise in the adjacent continuum in both stars. The synthesis of this line confirms a large overabundance of mercury, about +4.57 dex in HD 149121, and +3.70 dex in HD 178065, which is less than the excesses derived from the 3983.93 Å line in earlier studies. The presence of previously reported weak emission lines of Ti ii at 6106.50 Å and of Cr ii at 6158.62 and 6182.30 Å in the spectrum of HD 178065 is confirmed. The synthesis of other lines close to the Hg ii line yields estimates of the abundance deficiencies or excesses relative to solar abundances. Oxygen has a solar abundance (0.00 dex), silicon is deficient (−0.48 dex), iron also (−0.22 dex) and chromium is overabundant in HD 178065.