2007A&A...469.1069B

We provide observational material to study the magnetic field variability of the classical {beta} Cep-type star {gamma} Peg. The observations were carried out in the HeI 6678 line in the course of 23 observing nights from 1997 to 2005 with using the Coude spectrograph in spectropolarimetric mode at the Crimean 2.6m telescope. The behavior of stellar wind was studied in the UV region using data from the IUE satellite (the INES database). It is shown that the UV stellar wind exhibits a variability. A variation of the wind due to stellar pulsations has been detected. In the HeI 6678 line, the abnormally blueshifted radial velocities (γ=-60.57±0.29km/s) were detected during a single night in 2005. We do not confirm the 370.5-day orbital period. The most probable orbital period was estimated as P_orb=6.81608±0.00012day. The ratio P_orb/P_puls=44.92 appeared to be very close to integer. We have detected the presence of a weak magnetic field on the star. The longitudinal component of the field varies from -10G to 30G with the stellar rotation. The most probable rotational period is P_rot=6.6538±0.0016days. Both the orbital and the rotational periods are integral multiples of the difference between them: P_orb/|P_orb-P_rot|=42.002, and P_rot/|P_orb-P_rot|=41.002. Variation in the longitudinal magnetic field during the pulsation period with an amplitude about 7G was detected.