MOBSTER -- VII. Using light curves to infer magnetic and rotational properties of stars with centrifugal magnetospheres

Abstract

Early-type B stars with strong magnetic fields and rapid rotation form centrifugal magnetospheres (CMs), as the relatively weak stellar wind becomes magnetically confined and centrifugally supported above the Kepler co-rotation radius. CM plasma is concentrated at and above the Kepler co-rotation radius at the intersection between the rotation and magnetic field axis. Stellar rotation can cause these clouds of material to intersect the viewer's line-of-sight, leading to photometric eclipses. However, for stars with strong ($\sim 10\mathrm{kG}$) magnetic fields and rapid rotation, CMs can become optically thick enough for emission to occur via electron scattering. Using high-precision space photometry from a sample of stars with strong H$\alpha$ emission, we apply simulated light curves from the Rigidly Rotating Magnetosphere model to directly infer magnetic and rotational properties of these stars. By comparing the values inferred from photometric modelling to those independently determined by spectropolarimetry, we find that magnetic obliquity angle $\beta$, viewer inclination $i$ and critical rotation fraction $W$ can be approximately recovered for 3 of the 4 stars studied here. However, there are large discrepancies between the optical depth at the Kepler radius ${\tau }_{\mathrm{K}}$ expected from magnetometry, and the values required to match the observations. We show that ${\tau }_{\mathrm{K}}$ of order unity is needed to reasonably match the light curve morphology of our sample stars.

arXiv comment15 pages, 8 figures. Accepted for publication in MNRAS

References in corpus (67)

• The Transiting Exoplanet Survey Satellite
• Mass-loss predictions for O and B stars as a function of metallicity
• The K2 Mission: Characterization and Early results
• Dynamical Simulations of Magnetically Channeled Line-Driven Stellar Winds: I. Isothermal, Nonrotating, Radially Driven Flow
• A Magnetic Confinement vs. Rotation Classification of Massive-Star Magnetospheres
• Dynamical Simulations of Magnetically Channeled Line-Driven Stellar Winds: II. The Effects of Field-Aligned Rotation
• Dynamical Simulations of Magnetically Channeled Line-Driven Stellar Winds: III. Angular Momentum Loss and Rotational Spindown
• The MiMeS survey of magnetism in massive stars: Magnetic analysis of the O-type stars
• Evolutionary state of magnetic chemically peculiar stars
• OGLE-IV: Fourth Phase of the Optical Gravitational Lensing Experiment
• The Rigidly Rotating Magnetosphere of Sigma Ori E
• The Magnetic Early B-type Stars III: A main sequence magnetic, rotational, and magnetospheric biography
• The Magnetic Early B-type Stars I: Magnetometry and Rotation
• 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
• A Volume Limited Survey of mCP Stars Within 100pc II: Rotational and Magnetic Properties
• 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
• HR 5907: Discovery of the most rapidly rotating magnetic B-type star by the MiMeS Collaboration
• The effects of surface fossil magnetic fields on massive star evolution: I. Magnetic field evolution, mass-loss quenching and magnetic braking
• A Volume-Limited Survey of mCP Stars Within 100pc I: Fundamental Parameters and Chemical Abundances
• A three-dimensional model for the radio emission of magnetic chemically peculiar stars
• The light variability of the helium strong star HD 37776 as a result of its inhomogeneous elemental surface distribution
• Discovery of a magnetic field in the rapidly-rotating O-type secondary of the colliding-wind binary HD 47129 (Plaskett's star)
• MOBSTER -- VI. The crucial influence of rotation on the radio magnetospheres of hot stars
• MOBSTER - II. Identification of rotationally variable A stars observed with \emph{TESS} in Sectors 1 to 4
• Basic parameters and properties of the rapidly rotating magnetic helium strong B star HR7355
• An `Analytic Dynamical Magnetosphere' formalism for X-ray and optical emission from slowly rotating magnetic massive stars
• The nature of the light variability of the silicon star HR 7224
• Magnetic OB[A] Stars with TESS: probing their Evolutionary and Rotational properties (MOBSTER) - I. First-light observations of known magnetic B and A stars
• The effects of surface fossil magnetic fields on massive star evolution: II. Implementation of magnetic braking in MESA and implications for the evolution of surface rotation in OB stars
• The Magnetic Early B-type Stars IV: Breakout or Leakage? H$\alpha$ emission as a diagnostic of plasma transport in centrifugal magnetospheres
• A scaling relationship for non-thermal radio emission from ordered magnetospheres: from the top of the Main Sequence to planets
• Magnetic field topologies of the bright, weak-field Ap stars theta Aurigae and epsilon Ursae Majoris
• Discovery of a strong magnetic field in the rapidly rotating B2Vn star HR 7355
• MOST Observations of sigma Ori E: Challenging the Centrifugal Breakout Narrative
• Exploring the photometric signatures of magnetospheres around Helium-strong stars
• Magnetic field detection in the B2Vn star HR 7355
• The MiMeS survey of Magnetism in Massive Stars: Magnetic properties of the O-type star population
• How the breakout-limited mass in B-star centrifugal magnetospheres controls their circumstellar H-alpha emission
• Centrifugal breakout reconnection as the electron acceleration mechanism powering the radio magnetospheres of early-type stars
• The Magnetic Early B-type Stars II: stellar atmospheric parameters in the era of Gaia
• HD 156324: a tidally locked magnetic triple spectroscopic binary with a disrupted magnetosphere
• Ultraviolet and visual flux and line variations of one of the least variable Bp stars HD 64740
• Discovery of Two Rare Rigidly-Rotating Magnetosphere Stars in the APOGEE Survey
• B fields in OB stars (BOB): FORS2 spectropolarimetric follow-up of the two rare rigidly rotating magnetosphere stars HD23478 and HD345439
• The pulsating magnetosphere of the extremely slowly rotating magnetic $\beta$ Cep star ${\xi }^1$ CMa
• HD 164492C: a rapidly-rotating, H$\alpha$-bright, magnetic early B star associated with a 12.5d spectroscopic binary
• The most rapidly rotating He-strong emission line star: HR7355
• Diffusion-plus-drift models for the mass leakage from centrifugal magnetospheres of magnetic hot-stars
• A search for strong magnetic fields in massive and very massive stars in the Magellanic Clouds
• Polarimetric observations of $\sigma$ Orionis E
• Characterizing the Rigidly Rotating Magnetosphere Stars HD 345439 and HD 23478
• MOBSTER -- V: Discovery of a magnetic companion star to the magnetic $\beta$ Cep pulsator HD 156424
• Photometric identification of the periods of the first candidate extragalactic magnetic massive stars
• Modelling the photometric variability of magnetic massive stars with the Analytical Dynamical Magnetosphere model
• NGC 6611 601: A hot pre-main sequence spectroscopic binary containing a centrifugal magnetosphere host star
• The magnetic field and magnetosphere of Plaskett's star: A fundamental shift in our understanding of the system
• The pulsationally modulated radial crossover signature of the slowly rotating magnetic B-type star ${\xi }^1$ CMa
• Confirmation of xi^1 CMa's ultra-slow rotation: magnetic polarity reversal and a dramatic change in magnetospheric UV emission lines
• Trumpler 16-26: A New Centrifugal Magnetosphere Discovered via SDSS/APOGEE H-band Spectroscopy
• Electron Scattering Emission in the Light Curves of Stars with Centrifugal Magnetospheres
• Photometric signatures of corotating magnetospheres of hot stars governed by higher-order magnetic multipoles
• Could the Magnetic Star HD 135348 Possess a Rigidly Rotating Magnetosphere?
• News from Gaia on sigma Ori E: a case study for the wind magnetic braking process
• Untangling magnetic massive star properties with linear polarization variability and the Analytic Dynamical Magnetosphere model

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