2012A&A...545A.121K

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 6678Å emission component suggests that the star is the same 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 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 270km/s, 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 HeI 6678Å 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.