Research Note

o Puppis: another Be+sdO binary?^{⋆,⋆⋆,⋆⋆⋆}

¹ Astronomical Institute, Academy of Sciences of the Czech Republic, Fričova 298, 251 65 Ondřejov, Czech Republic
e-mail: koubsky@sunstel.asu.cas.cz
² Department of Theoretical Physics and Astrophysics, Masaryk University, Kotlářská 2, 611 37 Brno, Czech Republic

Received: 25 May 2012
Accepted: 10 August 2012

Abstract

The spectrum of the Be star o Pup is shown to vary periodically with a period of 28.9 days. A radial-velocity variable He i 6678 Å emission component suggests that the star is the same type as φ 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 φ 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 φ Per-type binaries. The radial velocity curves defined by the prominent emission peak in He i 6678 Å line and Hα + Paschen emission move in anti-phase. We suggest that o Pup is generically similar to φ Per-type systems and may represent the fourth case of a Be star with a hot subdwarf companion.