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In the present study time evolution of quasi-spherical polytropic accretion flow with toroidal magnetic field is investigated. The study especially focused the astrophysically important case in which the adiabatic exponent $\gamma=5/3$. In…

Astrophysics · Physics 2012-05-11 Alireza Khesali , Kazem Faghei

Previous analyses of magnetospheric accretion and outflow in classical T Tauri stars (CTTSs), within the context of both the X-wind model and other theoretical scenarios, have assumed a dipolar geometry for the stellar magnetic field if it…

Astrophysics · Physics 2009-11-13 Subhanjoy Mohanty , Frank H. Shu

We performed 3D MHD calculations of stream accretion in cataclysmic variable stars for which the white dwarf primary star possesses a strong and complex magnetic field. These calculations are motivated by observations of polars; cataclysmic…

High Energy Astrophysical Phenomena · Physics 2012-10-16 A. G. Zhilkin , D. V. Bisikalo , P. A. Mason

We consider the radial buoyancy of vertical magnetic field lines in radiation and gas pressure dominated accretion disks. We find that in addition to radial drift driven by turbulent diffusion and biased by the global field geometry, there…

Astrophysics · Physics 2009-10-28 Seok Jae Park , Ethan T. Vishniac

We examine the morphology of magnetic structures in thin plasma accretion discs, generalizing a stationary ideal MHD model to the time-dependent visco-resistive case. Our analysis deals with small scale perturbations to a central…

High Energy Astrophysical Phenomena · Physics 2015-06-11 Giovanni Montani , Jacopo Petitta

We present results of axisymmetric magnetohydrodynamic (MHD) simulations investigating the launching of jets and outflows from a magnetically diffusive accretion disk. The time evolution of the disk structure is self-consistently taken into…

High Energy Astrophysical Phenomena · Physics 2015-06-22 Deniss Stepanovs , Christian Fendt

A global mode is shown to be unstable to non-axisymmetric perturbations in a differentially rotating Keplerian disk containing either vertical or azimuthal magnetic fields. In an unstratified cylindrical disk model, using both global…

High Energy Astrophysical Phenomena · Physics 2022-09-13 Fatima Ebrahimi , Matthew Pharr

We present the results of axisymmetric simulations of MRI-driven accretion onto a rapidly rotating, magnetized star accreting in the propeller regime. The stellar magnetosphere corotates with the star, forming a centrifugal barrier at the…

Solar and Stellar Astrophysics · Physics 2015-06-15 Patrick S Lii , Marina M. Romanova , Galina V. Ustyugova , Alexander V. Koldoba , Richard V. E. Lovelace

Like their lower mass siblings, massive protostars can be expected to: a) be surrounded by circumstellar disks and b) launch magnetically-driven jets and outflows. The disk formation and global evolution is thereby controlled by advection…

Solar and Stellar Astrophysics · Physics 2023-01-18 André Oliva , Rolf Kuiper

Gravitational instability plays an important role in driving gas accretion in massive protostellar discs. Particularly strong is the global gravitational instability, which arises when the disc mass is of order 0.1 of the mass of the…

Astrophysics of Galaxies · Physics 2015-05-20 D. Harsono , R. D. Alexander , Yuri Levin

We construct models of the inner part of a transonic adiabatic accretion disc assuming constant specific angular momentum taking the vertical structure fully into account.\\ For comparison purposes, we construct the corresponding one…

Astrophysics · Physics 2015-06-24 J. C. B. Papaloizou , E. Szuszkiewicz

We examine the effects of a global magnetic field and outflow on radiatively inefficient accretion flow (RIAF) in the presence of magnetic resistivity. We find a self-similar solutions for the height integrated equations that govern the…

High Energy Astrophysical Phenomena · Physics 2017-05-24 Maryam Ghasemnezhad , Shahram Abbassi

We study the flow structure in 3D magnetohydrodynamic (MHD) simulations of accretion onto Sagittarius A* via the magnetized winds of the orbiting Wolf-Rayet stars. These simulations cover over 3 orders of magnitude in radius to reach…

High Energy Astrophysical Phenomena · Physics 2020-01-29 Sean M. Ressler , Eliot Quataert , James M. Stone

We present results of global three-dimensional (3D) magnetohydrodynamic (MHD) simulations of accretion onto magnetized stars where both the magnetic and rotational axes of the star are tilted about the rotational axis of the disc. We…

Solar and Stellar Astrophysics · Physics 2021-07-06 M. M. Romanova , A. V. Koldoba , G. V. Ustyugova , A. A. Blinova , D. Lai , R. V. E. Lovelace

Strong magnetization in accretion discs could resolve a number of outstanding issues related to stability and state transitions in low-mass X-ray binaries. However, it is unclear how real discs become strongly magnetized and, even if they…

High Energy Astrophysical Phenomena · Physics 2017-03-22 P. Chris Fragile , Aleksander Sadowski

We develop an analytical model for the accretion and gravitational drag on a point mass that moves hypersonically in the midplane of a gaseous disk with a Gaussian vertical density stratification. Such a model is of interest for studying…

Astrophysics of Galaxies · Physics 2015-06-12 J. Cantó , A. Esquivel. F. J. Sánchez-Salcedo , A. C. Raga

The traditional paradigm of viscosity-dominated evolution of protoplanetary discs has been recently challenged by magnetized disc winds. However, distinguishing wind-driven and turbulence-driven accretion through observations has been…

Earth and Planetary Astrophysics · Physics 2023-05-30 Yinhao Wu , Yi-Xian Chen , Haochang Jiang , Ruobing Dong , Enrique Macías , Min-Kai Lin , Giovanni P. Rosotti , Vardan Elbakyan

We present a novel approach to study the global structure of steady, axisymmetric, advective, geometrically thin, magnetohydrodynamic (MHD) accretion flow around black holes in full general relativity (GR). Considering ideal MHD conditions…

High Energy Astrophysical Phenomena · Physics 2022-10-05 Samik Mitra , Debaprasad Maity , Indu Kalpa Dihingia , Santabrata Das

Context. Current research has established magnetised disc winds as a promising way of driving accretion in protoplanetary discs. Aims. We investigate the evolution of large protoplanetary disc populations under the influence of magnetically…

Earth and Planetary Astrophysics · Physics 2023-06-21 Jesse Weder , Christoph Mordasini , Alexandre Emsenhuber

A three-dimensional numerical model for an accretion process investigation in the magnetosphere of a white dwarf in magnetic cataclysmic variables is developed. The model assumes that the white dwarf has a dipole magnetic field with its…

Solar and Stellar Astrophysics · Physics 2016-02-04 P. B. Isakova , A. G. Zhilkin , D. V. Bisikalo