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.
Based partly on observations collected with the Perek 2-m Telescope of the Ondřejov Observatory.This work has made use of the BeSS database, operated at LESIA, Observatoire de Meudon, France.The Ondrejov spectra are only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/545/A121