o Puppis: another Be+sdO binary?

P. Koubský1, L. Kotková1, V. Votruba1,2, M. Šlechta1, and Š. Dvoráková2

1Astronomical Institute, Academy of Sciences of the Czech Republic, Fri?ova 298, CZ-251 65 Ondrejov, Czech Republic
2Department of Theoretical Physics and Astrophysics, Masaryk University, Kotlárská 2, CZ-611 37 Brno, Czech Republic

The spectrum of the Be star o Pup is shown to vary periodically with a period of 28.9 days. A radial-velocity variable HeI 6678 Å emission component suggests that the star is type as phi Per, 59 Cyg and FY CMa, i.e. binaries consisting of a Be star and a hot companion that illuminates the Be star disk (also called phi Per-type binaries or Be+sdO binaries). The range of radial-velocity variations of the stronger emission component in the helium line observed in o Pup is about 270 km s-1, a value in good agreement with the range derived for phi Per-type binaries. The radial velocity curves defined by the prominent emission peak in HeI 6678 Å line and H-alpha + Paschen emission move in anti-phase. We suggest that o Pup is generically similar to phi Per-type systems and may represent the fourth case of a Be star with a hot subdwarf companion.

A&A, 2012, 545, A121
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