- Discovery of a magnetic field in the O9 sub-giant star HD 57682 by the MiMeS Collaboration
- Monthly Notices of the Royal Astronomical Society. Letters
- Volume | Issue number
- 400 | 1
- Pages (from-to)
- Document type
- Faculty of Science (FNWI)
- Anton Pannekoek Institute for Astronomy (API)
We report the detection of a strong, organized magnetic field in the O9IV star HD 57682, using spectropolarimetric observations obtained with ESPaDOnS at the 3.6-m Canada-France-Hawaii Telescope within the context of the Magnetism in Massive Stars (MiMeS) Large Programme. From the fitting of our spectra using non-local thermodynamic equilibrium model atmospheres, we determined that HD 57682 is a 17(-9)(+19)M(circle dot) star with a radius of 7.0(-1.8)(+2.4)R(circle dot) and a relatively low mass-loss rate of 1.4(-0.95)(+3.1) x 10(-9) M-circle dot yr(-1). The photospheric absorption lines are narrow, and we use the Fourier transform technique to infer v sin i = 15 +/- 3 km s(-1). This v sin i implies a maximum rotational period of 31.5 d, a value qualitatively consistent with the observed variability of the optical absorption and emission lines, as well as the Stokes V profiles and longitudinal field. Using a Bayesian analysis of the velocity-resolved Stokes V profiles to infer the magnetic field characteristics, we tentatively derive a dipole field strength of 1680(-356)(+134)G. The derived field strength and wind characteristics imply a wind that is strongly confined by the magnetic field.
- go to publisher's site
- DOI: 10.1111/j.1745-3933.2009.00771.x; eprintid: arXiv:0910.0214
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