Astronomy and Astrophysics – Astrophysics – Solar and Stellar Astrophysics
Scientific paper
2011-06-15
Astronomy and Astrophysics
Astrophysics
Solar and Stellar Astrophysics
10 pages, accepted by MNRAS
Scientific paper
This paper reports high-precision Stokes V spectra of HD 191612 acquired using the ESPaDOnS spectropolarimeter at the Canada-France-Hawaii Telescope, in the context of the Magnetism in Massive stars (MiMeS) Project. Using measurements of the equivalent width of the Halpha line and radial velocities of various metallic lines, we have updated both the spectroscopic and orbital ephemerides of this star. We confirm the presence of a strong magnetic field in the photosphere of HD 191612, and detect its variability. We establish that the longitudinal field varies in a manner consistent with the spectroscopic period of 537.6 d, in an approximately sinusoidal fashion. This demonstrates a firm connection between the magnetic field and the processes responsible for the line and continuum variability. Interpreting the variation of the longitudinal magnetic field within the context of the dipole oblique rotator model we obtain a best-fit surface magnetic field model with obliquity beta=67\pm 5 deg and polar strength Bd=2450\pm 400 G . The inferred magnetic field strength implies an equatorial wind magnetic confinement parameter eta*~50, supporting a picture in which the Halpha emission and photometric variability have their origin in an oblique, rigidly rotating magnetospheric structure resulting from a magnetically channeled wind. This interpretation is supported by our successful Monte Carlo radiative transfer modeling of the photometric variation, which assumes the enhanced plasma densities in the magnetic equatorial plane above the star implied by such a picture. Predictions of the continuum linear polarisation resulting from Thompson scattering from the magnetospheric material indicate that the Stokes Q and U variations are highly sensitive to the magnetospheric geometry, and that expected amplitudes are in the range of current instrumentation. (abridged)
Bouret Jean-Claud
Donati Jean-Francois
Doula A. ud
Fullerton Alex
Grunhut Jason H.
No associations
LandOfFree
Confirmation of the magnetic oblique rotator model for the Of?p star HD 191612 does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Confirmation of the magnetic oblique rotator model for the Of?p star HD 191612, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Confirmation of the magnetic oblique rotator model for the Of?p star HD 191612 will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-659141