The Magnetic Early B-type Stars I: Magnetometry and Rotation

Abstract

The rotational and magnetic properties of many magnetic hot stars are poorly characterized, therefore the MiMeS and BinaMIcS collaborations have collected extensive high-dispersion spectropolarimetric datasets of these targets. We present longitudinal magnetic field measurements $⟨B_{\mathrm{z}}⟩$ for 52 early B-type stars (B5 to B0), with which we attempt to determine their rotational periods $P_{\mathrm{rot}}$. Supplemented with high-resolution spectroscopy, low-resolution DAO circular spectropolarimetry, and archival Hipparcos photometry, we determined $P_{\mathrm{rot}}$ for 10 stars, leaving only 5 stars for which $P_{\mathrm{rot}}$ could not be determined. Rotational ephemerides for 14 stars were refined via comparison of new to historical magnetic measurements. The distribution of $P_{\mathrm{rot}}$ is very similar to that observed for the cooler Ap/Bp stars. We also measured $v\sin i$ and $v_{\mathrm{mac}}$ for all stars. Comparison to non-magnetic stars shows that $v\sin i$ is much lower for magnetic stars, an expected consequence of magnetic braking. We also find evidence that $v_{\mathrm{mac}}$ is lower for magnetic stars. LSD profiles extracted using single-element masks revealed widespread, systematic discrepancies in $⟨B_{\mathrm{z}}⟩$ between different elements: this effect is apparent only for chemically peculiar stars, suggesting it is a consequence of chemical spots. Sinusoidal fits to H line $⟨B_{\mathrm{z}}⟩$ measurements (which should be minimally affected by chemical spots), yielded evidence of surface magnetic fields more complex than simple dipoles in 6 stars for which this has not previously been reported; however, in all 6 cases the second- and third-order amplitudes are small relative to the first-order (dipolar) amplitudes.

arXiv comment38 pages, 47 figures, accepted for publication in MNRAS

References in corpus (79)

• Validation of the new Hipparcos reduction
• Magnetic fields of non-degenerate stars
• The rotation rates of massive stars: the role of binary interaction through tides, mass transfer and mergers
• The surprising magnetic topology of tauSco: fossil remnant or dynamo output?
• A fossil origin for the magnetic fields of A-stars and white dwarfs
• Present-day cosmic abundances. A comprehensive study of nearby early B-type stars and implications for stellar and Galactic evolution and interstellar dust models
• Least squares deconvolution of the stellar intensity and polarization spectra
• Be-star rotation: how close to critical?
• Axisymmetric magnetic fields in stars: relative strengths of poloidal and toroidal components
• Weak magnetic fields in Ap/Bp stars: Evidence for a dipole field lower limit and a tentative interpretation of the magnetic dichotomy
• The IACOB project: I. Rotational velocities in Northern Galactic O and early B-type stars revisited. The impact of other sources of line-broadening
• 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 IACOB project: III. New observational clues to understand macroturbulent broadening in massive O- and B-type stars
• Searching for links between magnetic fields and stellar evolution. I. A survey of magnetic fields in open cluster A- and B-type stars with FORS1
• The VLT-FLAMES Tarantula Survey X: Evidence for a bimodal distribution of rotational velocities for the single early B-type stars
• The Rigidly Rotating Magnetosphere of Sigma Ori E
• On non-axisymmetric magnetic equilibria in stars
• Transport and mixing in the radiation zones of rotating stars II. Axisymmetric magnetic field
• Collective pulsational velocity broadening due to gravity modes as a physical explanation for macroturbulence in hot massive stars
• Early magnetic B-type stars: X-ray emission and wind properties
• On the Stability of Non Force-Free Magnetic Equilibria in Stars
• B fields in OB stars (BOB): low-resolution FORS2 spectropolarimetry of the first sample of 50 massive stars
• Discovery of Rotational Braking in the Magnetic Helium-Strong Star Sigma Orionis E
• The extraordinary complex magnetic field of the helium-strong star HD 37776
• Centrifugal Breakout of Magnetically Confined Line-Driven Stellar Winds
• Periodic X-ray Emission from the O7 V Star theta^1 Orionis C
• Detection of a magnetic field on HD108: clues to extreme magnetic braking and the Of?p phenomenon
• Confirmation of the magnetic oblique rotator model for the Of?p star HD 191612
• Revisiting the Rigidly Rotating Magnetosphere model for sigma Ori E. I. Observations and Data Analysis
• B fields in OB stars (BOB): Concluding the FORS2 observing campaign
• HR 5907: Discovery of the most rapidly rotating magnetic B-type star by the MiMeS Collaboration
• The search for magnetic fields in mercury-manganese stars
• The FORS1 catalogue of stellar magnetic field measurements
• New magnetic field measurements of beta Cephei stars and Slowly Pulsating B stars
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• Basic parameters and properties of the rapidly rotating magnetic helium strong B star HR7355
• The spectral variability and magnetic field characteristics of the Of?p star HD 148937
• On magnetic inhibition of photospheric macro-turbulence generated in the iron-bump opacity zone of O-stars
• Massive pulsating stars observed by BRITE-Constellation. I. The triple system Beta Centauri (Agena)
• Discovery of a strong magnetic field in the rapidly rotating B2Vn star HR 7355
• Surprising variations in the rotation of the chemically peculiar stars CU Virginis and V901 Orionis
• The detection of variable radio emission from the fast rotating magnetic hot B-star HR7355 and evidence for its X-ray aurorae
• Discovery of new magnetic early-B stars within the MiMeS HARPSpol survey
• Detection of magnetic fields in both B-type components of the $\epsilon$ Lupi system: a new constraint on the origin of fossil fields?
• Stellar magnetic field parameters from a Bayesian analysis of high-resolution spectropolarimetric observations
• On the consistency of magnetic field measurements of Ap stars: lessons learned from the FORS1 archive
• Rotation, spectral variability, magnetic geometry and magnetosphere of the Of?p star CPD -28 2561
• Magnetic field detection in the B2Vn star HR 7355
• Critical evaluation of magnetic field detections reported for pulsating B-type stars in the light of ESPaDOnS, Narval and reanalyzed FORS1/2 observations
• Magnetic field topology and chemical abundance distributions of the young, rapidly rotating chemically peculiar star HR5624
• Discovery of the magnetic field in the pulsating B star beta Cephei
• Wind Circulation in Selected Rotating Magnetic Early-B Stars
• B fields in OB stars (BOB): on the detection of weak magnetic fields in the two early B-type stars beta CMa and epsilon CMa
• The surface magnetic field and chemical abundance distributions of the B2V helium-strong star HD184927
• HD 156324: a tidally locked magnetic triple spectroscopic binary with a disrupted magnetosphere
• The rotation rates of massive stars: How slow are the slow ones?
• First HARPSpol discoveries of magnetic fields in massive stars
• The Discovery of a Strong Magnetic Field and Co-rotating Magnetosphere in the Helium-weak Star HD 176582
• First detections of 610 MHz radio emission from hot magnetic stars
• A novel and sensitive method for measuring very weak magnetic fields of DA white dwarfs: A search for a magnetic field at the 250 G level in 40 Eri B
• B fields in OB stars (BOB): The discovery of a magnetic field in a multiple system in the Trifid Nebula, one of the youngest star forming regions
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• The magnetic field and spectral variability of the He-weak star HR 2949
• The orbit of the close spectroscopic binary epsilon Lupi and the intrinsic variability of its early B-type components
• The pulsating magnetosphere of the extremely slowly rotating magnetic $\beta$ Cep star ${\xi }^1$ CMa
• HD 35502: a hierarchical triple system with a magnetic B5IVpe primary
• B fields in OB stars (BOB): FORS2 spectropolarimetric follow-up of the two rare rigidly rotating magnetosphere stars HD23478 and HD345439
• HD 164492C: a rapidly-rotating, H$\alpha$-bright, magnetic early B star associated with a 12.5d spectroscopic binary
• An infrared diagnostic for magnetism in hot stars
• An Inexpensive Liquid Crystal Spectropolarimeter for the Dominion Astrophysical Observatory Plaskett Telescope
• The IACOB project: IV. New predictions for high-degree non-radial mode instability domains in massive stars and connection with macroturbulent broadening
• Discovery of a magnetic field in the early B-type star sigma Lupi
• Weak magnetic field, solid-envelope rotation, and wave-induced N-enrichment in the SPB star $\zeta$ Cassiopeiae
• The challenge of measuring magnetic fields in strongly pulsating stars: the case of HD 96446
• Discovery of magnetic fields in three He variable Bp stars with He and Si spots
• Extensive study of HD 25558, a long-period double-lined binary with two SPB components
• Identification of pulsational modes in rotating slowly pulsating B-type stars

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