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

Abstract

We report the detection of a strong, organised 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 Program. From the fitting of our spectra using NLTE model atmospheres we determined that HD 57682 is a $17_{-9}^{+19}$ M${}_{\odot }$ star with a radius of $7.0_{-1.8}^{+2.4}$ R${}_{\odot }$, and a relatively low mass-loss rate of $1.4_{-0.95}^{+3.1}\times 10^{-9}$ M${}_{\odot }$ yr${}^{-1}$. The photospheric absorption lines are narrow, and we use the Fourier transform technique to infer $v\sin i=15\pm 3$ 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.

6 pages, 5 figures. Accepted for publication in MNRAS Letters

References in corpus (12)

• Dynamical Simulations of Magnetically Channeled Line-Driven Stellar Winds: II. The Effects of Field-Aligned Rotation
• Analysis of Galactic late-type O dwarfs: more constraints on the weak wind problem
• Magnetic field measurements of O stars with FORS1 at the VLT
• Adaptive Optics Photometry and Astrometry of Binary Stars. III. A Faint Companion Search of O-Star Systems
• Discovery of two magnetic massive stars in the Orion Nebula Cluster: a clue to the origin of neutron star magnetic fields?
• The weak magnetic field of the O9.7 supergiant zeta Orionis A
• On the incidence of magnetic fields in slowly-pulsating B, Beta Cephei and B-type emission line stars
• New magnetic field measurements of beta Cephei stars and Slowly Pulsating B stars
• The magnetic field and confined wind of the O star ${\theta }^1$~Orionis~C
• Magnetic field measurements and wind-line variability of OB-type stars
• Discovery of magnetic fields in the very young, massive stars W601 (NGC 6611) and OI 201 (NGC 2244)
• Chandra spectroscopy of the hot star beta Crucis and the discovery of a pre-main-sequence companion

Cited by in corpus (41)

• The Galactic O-Star Spectroscopic Survey. I. Classification System and Bright Northern Stars in the Blue-Violet at R~2500
• A Magnetic Confinement vs. Rotation Classification of Massive-Star Magnetospheres
• The MiMeS Survey of Magnetism in Massive Stars: Introduction and overview
• The MiMeS survey of magnetism in massive stars: Magnetic analysis of the O-type stars
• The magnetic field of Betelgeuse: a local dynamo from giant convection cells?
• On the Stability of Non Force-Free Magnetic Equilibria in Stars
• Variability of OB stars from TESS southern Sectors 1-13 and high-resolution IACOB and OWN spectroscopy
• The MiMeS Survey of Magnetism in Massive Stars: CNO surface abundances of Galactic O stars
• NGC 1624-2: A slowly rotating, X-ray luminous Of?cp star with an extraordinarily strong magnetic field
• The effects of surface fossil magnetic fields on massive star evolution: I. Magnetic field evolution, mass-loss quenching and magnetic braking
• Observational effects of magnetism in O stars: surface nitrogen abundances
• Investigating the spectroscopic, magnetic and circumstellar variability of the O9 subgiant star HD 57682
• Magnetic fields in massive stars, their winds, and their nebulae
• Evidence of magnetic field decay in massive main-sequence stars
• What Sets the Initial Rotation Rates of Massive Stars?
• Discovery of new magnetic early-B stars within the MiMeS HARPSpol survey
• First HARPSpol discoveries of magnetic fields in massive stars
• Blue supergiants as descendants of magnetic main sequence stars
• The X-ray catalog of spectroscopically identified Galactic O stars: Investigating the dependence of X-ray luminosity on stellar and wind parameters
• First detections of 610 MHz radio emission from hot magnetic stars
• Testing the fossil field hypothesis: could strongly magnetised OB stars produce all known magnetars?
• The magnetic characteristics of Galactic OB stars from the MiMeS survey of magnetism in massive stars
• Detectability of small-scale magnetic fields in early-type stars
• Magnetometry of a sample of massive stars in Carina
• Quantitative spectroscopy of late O-type main-sequence stars with a hybrid non-LTE method
• Extreme resonance line profile variations in the ultraviolet spectra of NGC 1624-2: probing the giant magnetosphere of the most strongly magnetized known O-type star
• The changing UV and X-ray properties of the Of?p star CPD -28 2561
• X-ray diagnostics of massive star winds
• HST/STIS spectroscopy of the magnetic Of?p star HD 108: the low state at ultraviolet wavelengths
• A combined HST and XMM-Newton campaign for the magnetic O9.7 V star HD 54879: towards constraining the weak-wind problem of massive stars
• New self-consistent wind parameters fitting optical spectra of O-type stars observed with HERMES spectrograph
• Magnetic field geometry and magnetospheric environment of the strongly magnetic Of?p star NGC 1624-2
• Ultraviolet Spectropolarimetric Diagnostics of Hot Star Magnetospheres
• The Hanle Effect as a Diagnostic of Magnetic Fields in Stellar Envelopes. V. Thin Lines from Keplerian Disks
• The kinematic characteristics of magnetic O-type stars
• New Insights into the Puzzling P-Cygni Profiles of Magnetic Massive Stars
• Observations of magnetic fields in hot stars
• Surface magnetism of cool giant and supergiant stars
• Mixing in two magnetic OB stars discovered by the MiMeS collaboration
• A MiMeS analysis of the magnetic field and circumstellar environment of the weak-wind O9 sub-giant star HD 57682
• A magnetic field detection in the massive O-type bright giant 63 Oph