arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 1107.0883astro-ph.SR
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大振幅β造父变星V1449 Aql的强磁场

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

S. Hubrig, I. Ilyin, M. Briquet, M. Schoeller, J. F. Gonzalez, N. Nunez, P. De Cat, T. Morel

摘要:

只有极少数的仙王座β星的磁场的行为在旋转周期进行了研究。在过去的两年中,我们已经获得了多历元偏振光谱的β仙王座恒星V1449 Aql与SOFIN在北欧光学望远镜搜索的旋转周期和约束的几何形状的磁场。平均纵向磁场测量在13个不同的时期。新的测量,连同以前的FORS 1测量,已被用于频率分析和表征的磁场。V1449 Aql拥有迄今为止最强的纵向磁场,在仙王座β星中高达700 G。由此得到的周期图显示出三个主峰,最高峰位于f= 0.0720 d ^-1处,对应的周期为P= 13.893 d。磁场的几何形状可以用一个中心偶极子来描述,其极磁场强度B_d约为3 kG,磁轴与旋转轴的倾角β为76 ± 4 °。到目前为止,最强的纵向磁场是在仙王座β星V1449 Aql和xi ^1 CMa中探测到的,它们具有很大的径向速度振幅。它们的峰间振幅分别达到~ 90 km/s和~ 33 km/s。最后,我们简要地讨论了目前已知的八颗仙王座β星和候选仙王座β星在赫兹-罗素(H-R)图中的位置。

英文摘要:

Only for very few beta 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 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. The mean longitudinal magnetic field is measured at 13 different epochs. The new measurements, together with the previous FORS1 measurements, have been used for the frequency analysis and the characterization of the magnetic field. V1449 Aql so far possesses the strongest longitudinal magnetic field of up to 700G among the beta Cephei stars. The resulting periodogram displays three dominant peaks with the highest peak at f=0.0720d^-1 corresponding to a period P=13.893d. The magnetic field geometry can likely be described by a centred dipole with a polar magnetic field strength B_d around 3kG and an inclination angle beta of the magnetic axis to the rotation axis of 76+-4deg. As of today, the strongest longitudinal magnetic fields are detected in the beta Cephei stars V1449 Aql and xi^1 CMa with large radial velocity amplitudes. Their peak-to-peak amplitudes reach ~90km/s and ~33km/s, respectively. Concluding, we briefly discuss the position of the currently known eight magnetic beta Cephei and candidate beta Cephei stars in the Hertzsprung-Russell (H-R) diagram.

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