Discovery of a magnetic field in the O9 sub-giant star HD 57682 by the MiMeS Collaboration

Grunhut, H (author)

Wade, A (author)

Marcolino, F (author)

Petit, V (author)

Henrichs, F (author)

Cohen, H (author)

Alecian, E (author)

Bohlender, D (author)

Bouret, J.-C. (author)

Kochukhov, O (author): Uppsala universitet,Institutionen för fysik och astronomi

Neiner, C (author)

St-Louis, N (author)

Townsend, D (author)

(creator_code:org_t)

Oxford University Press (OUP), 2009
2009
English.
In: Monthly notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 0035-8711 .- 1365-2966 .- 1745-3925 .- 1745-3933. ; 400:1, s. L94-L98

Related links:: https://academic.oup...; show more...; https://urn.kb.se/re...; https://doi.org/10.1...; show less...

Abstract Subject headings

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.

By the author/editor: Grunhut, H; Wade, A; Marcolino, F; Petit, V; Henrichs, F; Cohen, H; show more...; Alecian, E; Bohlender, D; Bouret, J.-C.; Kochukhov, O; Neiner, C; St-Louis, N; Townsend, D; show less...

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