The strong magnetic field of the large-amplitude beta-Cephei pulsator V1449 Aql

S. HUBRIG; I. ILYIN; M. BRIQUET; M. SCHÖLLER; J. F. GONZÁLEZ; N. E. NUÑEZ; P. DE CAT; T. MOREL

ASTRONOMY AND ASTROPHYSICS

EDP SCIENCES S A

Lugar: Massachusetts ; Año: 2011

0004-6361

Context. Only for very few beta- Cephei stars has the behavior of the magnetic field been studied over the rotation cycle. Aims. During the last two years we obtained multi-epoch polarimetric spectra of the beta-Cephei star V1449 Aql with SOFIN at the Nordic Optical Telescope to search for a rotation period and to constrain the geometry of the magnetic field. Methods. The mean longitudinal magnetic field is measured on 13 different epochs. The new measurements together with the previous FORS 1 measurements have been used for the frequency analysis and the characterization of the magnetic field.Results. V1449 Aql possesses so far the strongest longitudinal magnetic field of up to 700G among the beta-Cephei stars. The search of a rotation period resulted in P = 13.893± 0.003 d. The magnetic field geometry can likely be described by a centred dipole with a polar magnetic field strength Bd around 3 kG and an inclination angle beta of the magnetic axis to the rotation axis of 76+-4°. As of today, the strongest longitudinal magnetic fields are detected in the beta-Cephei stars V1449Aql and xi-CMa with large radial velocity amplitudes. Their peak-to-peak amplitudes reach 90 km s-1and 33 km s-1, respectively. Concluding, we briefly discuss the position of the currently known eight magnetic beta-Cephei and candidate beta-Cephei stars in the H-R diagram.p { margin-bottom: 0.21cm; }