Discovery of a magnetic field in the O9 sub-giant star HD 57682 by the MiMeS Collaboration
2009 (English)In: Monthly notices of the Royal Astronomical Society, ISSN 0035-8711, E-ISSN 1365-2966, Vol. 400, no 1, L94-L98 p.Article in journal (Refereed) Published
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.
Place, publisher, year, edition, pages
2009. Vol. 400, no 1, L94-L98 p.
stars: early-type, stars: individual: HD 57682, stars: magnetic fields, stars: rotation, stars: winds, outflows
IdentifiersURN: urn:nbn:se:uu:diva-127415DOI: 10.1111/j.1745-3933.2009.00771.xISI: 000271708900021OAI: oai:DiVA.org:uu-127415DiVA: diva2:329893