2006A&A...448..697C

High resolution and high signal to noise ratio spectroscopic observations of the classical β Cephei star γ Peg were obtained between 1991 and 2005. The analysis of these data combined with previously published results shows that γ Peg is a spectroscopic binary with an orbital period of 370.5d. We discovered three new frequencies in addition to the well-known 6.5897d^–1 (0.15175d) one. That at 6.01d^–1 is a typical β Cephei frequency. The two others at 0.68 and 0.87d^–1 are similar to the high degree g-mode frequencies found in SPB stars. Thus, γ Peg is a hybrid β Cephei-SPB star. Its position in the HR diagram is compatible with such a status. In addition, a small increase of the main period has been detected between the 1995 and 2005 observations.