The SDSS/APOGEE Catalog of HgMn Stars

Abstract

We report on $H$-band spectra of chemically peculiar Mercury-Manganese (HgMn) stars obtained via the SDSS/APOGEE survey. As opposed to other varieties of chemically peculiar stars such as classical Ap/Bp stars, HgMn stars lack strong magnetic fields and are defined by extreme overabundances of Mn, Hg, and other heavy elements. A satisfactory explanation for the abundance patterns remains to be determined, but low rotational velocity is a requirement and involvement in binary/multiple systems may be as well. The APOGEE HgMn sample currently consists of 269 stars that were identified among the telluric standard stars as those whose metallic absorption content is limited to or dominated by the $H$-band Mn II lines. Due to the fainter magnitudes probed by the APOGEE survey as compared to past studies, only 9/269 stars in the sample were previously known as HgMn types. The 260 newly-identified HgMn stars represents a more than doubling of the known sample. At least 32% of the APOGEE sample are found to be binary or multiple systems, and from multi-epoch spectroscopy, we were able to determine orbital solutions for at least one component in 32 binaries. Many of the multi-lined systems include chemically peculiar companions, with noteworthy examples being the HgMn+Ap/Bp binary HD 5429, the HgMn+HgMn binary HD 298641, and the HgMn+BpMn+Am triple system HD 231263. As a further peculiarity, roughly half of the sample produces narrow emission in the C I 16895 angstroms line, with widths and radial velocities that match those of the Mn II lines.

References in corpus (8)

• The 2.5 m Telescope of the Sloan Digital Sky Survey
• The Apache Point Observatory Galactic Evolution Experiment (APOGEE) Spectrographs
• Target Selection for the SDSS-IV APOGEE-2 Survey
• High-resolution, H band Spectroscopy of Be Stars with SDSS-III/APOGEE: I. New Be Stars, Line Identifications, and Line Profiles
• Discovery of Resolved Magnetically Split Lines in SDSS/APOGEE Spectra of 157 Ap/Bp Stars
• Four new HgMn stars: HD 18104, HD 30085, HD 32867, HD 53588
• A Spectroscopic and Photometric Investigation of the Mercury-Manganese Star KIC 6128830
• Detection of weak magnetic fields in two HgMn stars

Cited by in corpus (10)

• Final Targeting Strategy for the SDSS-IV APOGEE-2S Survey
• Stellar labels for hot stars from low-resolution spectra - I. the HotPayne method and results for 330,000 stars from LAMOST DR6
• TESS survey of rotational and pulsational variability of mercury-manganese stars
• An Interpretable Machine Learning Framework for Modeling High-Resolution Spectroscopic Data
• V680 Mon -- a young mercury-manganese star in an eclipsing heartbeat system
• Visual Orbits of Spectroscopic Binaries with the CHARA Array. IV. HD 61859, HD 89822, HD 109510, and HD 191692
• New eclipsing binaries with mercury-manganese stars
• The evolutionary state of the chemically peculiar members of the open cluster NGC2516
• Chemically peculiar stars on the pre-main sequence
• A rare phosphorus-rich star in an eclipsing binary from TESS