Four new HgMn stars: HD 18104, HD 30085, HD 32867, and HD 53588.

Context. We have discovered four new HgMn stars while monitoring a sample of apparently slowly rotating superficially normal bright late-B and early-A stars in the northern hemisphere. Aims. Important classification lines of Hg II and Mn II are found as conspicuous features in the high resolution SOPHIE spectra of these stars (R = 75 000). Methods. Several lines of Hg II, Mn II and Fe II were synthesized using model atmospheres and the spectrum synthesis code SYNSPEC48, including hyperfine structure of various isotopes when relevant. These synthetic spectra were compared to high-resolution observations of these stars that have a high signal-to-noise ratio to derive abundances of these key elements. Results. The four stars are found to have distinct enhancements of Hg and Mn, which shows that they are not superficially normal B and A stars, but are new HgMn stars and need to be reclassified as such. [ABSTRACT FROM AUTHOR]