CPD-20 1123 (Albus 1) is a bright He-B Subdwarf

Abstract

Based on photometric and astrometric data it has been proposed that Albus 1 (also known as CPD-20 1123) might be a hot white dwarf similar to G191-B2B or, alternatively, a hot subdwarf. We obtained a series of optical spectra showing that CPD-20 1123 is a bright He-B subdwarf. We analyzed the HI Balmer and HeI line spectra and measured T_eff = 19800+/-400 K, log g = 4.55+/-0.10, and log N(He)/N(H) = 0.15+/-0.15. This peculiar object belongs to a family of evolved helium-rich stars that may be the products of double-degenerate mergers, or, alternatively, the products of post horizontal- or giant-branch evolution.

Accepted for publication in The Astrophysical Journal Letters

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• Hot subdwarf stars in close-up view IV. Helium abundances and the ${}^3$He isotopic anomaly of subdwarf B star
• EVR-CB-004: An Inflated Hot Subdwarf O star + Unseen WD Companion in a Compact Binary Discovered with the Evryscope
• A 500 pc volume-limited sample of hot subluminous stars II. Atmospheric parameters, mass distribution, and kinematics
• Finding the most variable stars in the Orion Belt with the All Sky Automated Survey
• NLTE spectral analysis of the intermediate helium-rich subdwarf B star CPD-20°1123