3D MHD simulations and synthetic radio emission from an oblique rotating magnetic massive star

Abstract

We have performed 3D isothermal MHD simulation of a magnetic rotating massive star with a non-zero dipole obliquity and predicted the radio/sub-mm observable lightcurves and continuum spectra for a frequency range compatible with ALMA. From these results we also compare the model input mass-loss to that calculated from the synthetic thermal emission. Spherical and cylindrical symmetry is broken due to the obliquity of the stellar magnetic dipole resulting in an inclination and phase dependence of both the spectral flux and inferred mass-loss rate, providing testable predictions of variability for oblique rotator. Both quantities vary by factors between 2 and 3 over a full rotational period of the star, demonstrating that the role of rotation as critical in understanding the emission. This illustrates the divergence from a symmetric wind, resulting in a two armed spiral structure indicative of a oblique magnetic rotator. We show that a constant spectral index, $\alpha$, model agrees well with our numerical prediction for a spherical wind for $\nu <10^3\mathrm{GHz}$, however it is unable to capture the behavior of emission at $\nu >10^3\mathrm{GHz}$. As such we caution the use of such constant $\alpha$ models for predicting emission from non-spherical winds such as those which form around magnetic massive stars.

arXiv comment19 pages, 14 figures

References in corpus (31)

• PLUTO: a Numerical Code for Computational Astrophysics
• Dynamical Simulations of Magnetically Channeled Line-Driven Stellar Winds: I. Isothermal, Nonrotating, Radially Driven Flow
• Sub-surface convection zones in hot massive stars and their observable consequences
• 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
• MPI-AMRVAC 2.0 for Solar and Astrophysical Applications
• The MiMeS Survey of Magnetism in Massive Stars: Introduction and overview
• An Extension of the Athena++ Code Framework for GRMHD Based on Advanced Riemann Solvers and Staggered-Mesh Constrained Transport
• M-dwarf stellar winds: the effects of realistic magnetic geometry on rotational evolution and planets
• 3D Models of Radiatively Driven Colliding Winds In Massive O+O Star Binaries: I. Hydrodynamics
• Mass loss in main-sequence B stars
• Accurate determination of the free-free Gaunt factor; I - non-relativistic Gaunt factors
• 2D wind clumping in hot, massive stars from hydrodynamical line-driven instability simulations using a pseudo-planar approach
• A Rigid-Field Hydrodynamics approach to modeling the magnetospheres of massive stars
• The Effect of Magnetic Field Tilt and Divergence on the Mass Flux and Flow Speed in a Line-Driven Stellar Wind
• BRITE-Constellation high-precision time-dependent photometry of the early-O-type supergiant $\zeta$ Puppis unveils the photospheric drivers of its small- and large-scale wind structures
• Transit Variability in Bow Shock-Hosting Planets
• Magnetic fields in massive stars, their winds, and their nebulae
• An `Analytic Dynamical Magnetosphere' formalism for X-ray and optical emission from slowly rotating magnetic massive stars
• Line-driven ablation of circumstellar disks: I. Optically thin decretion disks of classical Oe/Be stars
• Detection of magnetic fields in both B-type components of the $\epsilon$ Lupi system: a new constraint on the origin of fossil fields?
• MOVES II. Tuning in to the radio environment of HD189733b
• The BinaMIcS project: understanding the origin of magnetic fields in massive stars through close binary systems
• The Solar Wind in Time II: 3D stellar wind structure and radio emission
• Characterizing the turbulent porosity of stellar-wind structure generated by the line-deshadowing instability
• Disruption of circumstellar discs by large-scale stellar magnetic fields
• The magnetic characteristics of Galactic OB stars from the MiMeS survey of magnetism in massive stars
• A JVLA survey of the high frequency radio emission of the massive magnetic B- and O-type stars
• 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
• Sub-mm free-free emission from the winds of massive stars in the age of ALMA

Cited by in corpus (10)

• MOBSTER -- VI. The crucial influence of rotation on the radio magnetospheres of hot stars
• A scaling relationship for non-thermal radio emission from ordered magnetospheres: from the top of the Main Sequence to planets
• How the breakout-limited mass in B-star centrifugal magnetospheres controls their circumstellar H-alpha emission
• PION: Simulating bow shocks and circumstellar nebulae
• Simulations of the line-driven instability in magnetic hot star winds
• 3D MHD models of the centrifugal magnetosphere from a massive star with an oblique dipole field
• Modeling Magnetically Channeled Winds in 3D: I. Isothermal Simulations of a Magnetic O Supergiant
• Simulating stellar coronal rain and slingshot prominences
• A scaling relationship for non-thermal radio emission from ordered magnetospheres - II. Investigating the efficiency of relativistic electron production in magnetospheres of BA-type stars
• Radio Spectral Energy Distributions for Single Massive Star Winds with Free-Free and Synchrotron Emission