Determination of the Abundance of Mercury from the Hg ii Line at 5677.10 Å in Late B-type Stars. VIII. HD 175640

Abstract

The weak line of Hg ii located at 5677.10 Å is detected as a faint 1% absorption feature in a NARVAL spectrum of the sharp-lined HgMn star HD 175640. The synthesis of this Hg ii feature yields a mercury excess, about +4.00 dex, which is far lower than the +4.40 dex excess derived from the Hg ii line at 3983.93 Å. I suggest that the Hg ii line at 5677.10 Å is very weak because it is filled by emission in its core, a proposal which had previously been made to explain the weakness of the Hg ii line at 6149.47 Å in HD 175640. Several emission lines ascribed to Ti ii and Mn ii are present in the red part of the spectrum. The synthesis of selected lines of several other elements yields abundances which agree fairly well with those previously derived.