The strong magnetic field of the large-amplitude β Cephei pulsator V1449 Aquilae
English
Hubrig, S.[Leibniz-Institut für Astrophysik Potsdam (AIP), An der Sternwarte 16, 14482, Potsdam, Germany]
Ilyin, I.[Leibniz-Institut für Astrophysik Potsdam (AIP), An der Sternwarte 16, 14482, Potsdam, Germany]
Briquet, Maryline[Université de Liège - ULg > Département d'astrophys., géophysique et océanographie (AGO) > Astrophysique stellaire théorique et astérosismologie]
González, J. F.[Instituto de Ciencias Astronomicas, de la Tierra, y del Espacio (ICATE), 5400, San Juan, Argentina]
Nuñez, N.[Instituto de Ciencias Astronomicas, de la Tierra, y del Espacio (ICATE), 5400, San Juan, Argentina]
De Cat, P.[Koninklijke Sterrenwacht van België, Ringlaan 3, 1180, Brussel, Belgium]
Morel, Thierry[Université de Liège - ULg > Département d'astrophys., géophysique et océanographie (AGO) > Groupe d'astrophysique des hautes énergies (GAPHE)]
[en] stars: early-type ; stars: rotation ; stars: individual: V1449 Aql ; stars: magnetic field ; stars: oscillations ; stars: variables: general
[en] <BR /> Aims: Only for very few β Cephei stars has the behaviour of the magnetic field been studied over the rotation cycle. During the past two years we have obtained multi-epoch polarimetric spectra of the β 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. <BR /> Methods: The mean longitudinal magnetic field is measured at 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. <BR /> Results: V1449 Aql so far possesses the strongest longitudinal magnetic field of up to 700 G among the β Cephei stars. The resulting periodogram displays three dominant peaks with the highest peak at f = 0.0720 d[SUP]-1[/SUP] corresponding to a period P = 13ḍ893. The magnetic field geometry can likely be described by a centred dipole with a polar magnetic field strength B[SUB]d[/SUB] around 3 kG and an inclination angle β of the magnetic axis to the rotation axis of 76 ± 4°. As of today, the strongest longitudinal magnetic fields are detected in the β Cephei stars V1449 Aql and ξ[SUP]1[/SUP] CMa with large radial velocity amplitudes. Their peak-to-peak amplitudes reach ~90 km s[SUP]-1[/SUP] and ~33 km s[SUP]-1[/SUP], respectively. Concluding, we briefly discuss the position of the currently known eight magnetic β Cephei and candidate β Cephei stars in the Hertzsprung-Russell (H-R) diagram. Based on observations obtained at the 2.56-m Nordic Optical Telescope on La Palma and ESO Prgs. 077.D-0311 and 178.D-0361.Appendix A is available in electronic form at <A href="http://www.aanda.org">http://www.aanda.org</A>
[Leibniz-Institut für Astrophysik Potsdam (AIP), An der Sternwarte 16, 14482, Potsdam, Germany]
