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Related papers: Hall Effect in Protostellar Disc Formation and Evo…

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Non-ideal MHD effects have been shown recently as a robust mechanism of averting the magnetic braking "catastrophe" and promoting protostellar disc formation. However, the magnetic diffusivities that determine the efficiency of non-ideal…

Solar and Stellar Astrophysics · Physics 2021-05-12 Bo Zhao , Paola Caselli , Zhi-Yun Li , Ruben Krasnopolsky , Hsien Shang , Ka Ho Lam

Stars form in dense cores of molecular clouds that are observed to be significantly magnetized. A dynamically important magnetic field presents a significant obstacle to the formation of protostellar disks. Recent studies have shown that…

Solar and Stellar Astrophysics · Physics 2015-05-27 Ruben Krasnopolsky , Zhi-Yun Li , Hsien Shang

Magnetic fields play an important role in star formation by regulating the removal of angular momentum from collapsing molecular cloud cores. Hall diffusion is known to be important to the magnetic field behaviour at many of the…

Solar and Stellar Astrophysics · Physics 2015-05-30 Catherine R. Braiding , Mark Wardle

We characterize magnetically driven accretion at radii between 1 au and 100 au in protoplanetary discs, using a series of local non-ideal magnetohydrodynamic (MHD) simulations. The simulations assume a Minimum Mass Solar Nebula (MMSN) disc…

Solar and Stellar Astrophysics · Physics 2015-10-07 Jacob B. Simon , Geoffroy Lesur , Matthew W. Kunz , Philip J. Armitage

We demonstrate the formation of gravitationally unstable discs in magnetized molecular cloud cores with initial mass-to-flux ratios of 5 times the critical value, effectively solving the magnetic braking catastrophe. We model the…

Solar and Stellar Astrophysics · Physics 2018-08-22 James Wurster , Matthew R. Bate , Daniel J. Price

Magnetic fields have been shown both observationally and through theoretical work to be an important factor in the formation of protostars and their accretion disks. Accurate modelling of the evolution of the magnetic field in…

Dense, star-forming, cores of molecular clouds are observed to be significantly magnetized. A realistic magnetic field of moderate strength has been shown to suppress, through catastrophic magnetic braking, the formation of a rotationally…

Astrophysics of Galaxies · Physics 2015-05-28 Zhi-Yun Li , Ruben Krasnopolsky , Hsien Shang

We perform 3D stratified shearing-box MHD simulations on the gas dynamics of protoplanetary disks threaded by net vertical magnetic field Bz. All three non-ideal MHD effects, Ohmic resistivity, the Hall effect and ambipolar diffusion are…

Earth and Planetary Astrophysics · Physics 2015-06-22 Xue-Ning Bai

The transport of angular momentum by magnetic fields is a crucial physical process in formation and evolution of stars and disks. Because the ionization degree in star forming clouds is extremely low, non-ideal magnetohydrodynamic (MHD)…

Solar and Stellar Astrophysics · Physics 2015-06-23 Kengo Tomida , Satoshi Okuzumi , Masahiro N. Machida

It has been shown that a realistic level of magnetization of dense molecular cloud cores can suppress the formation of a rotationally supported disk (RSD) through catastrophic magnetic braking in the axisymmetric ideal MHD limit. In this…

Solar and Stellar Astrophysics · Physics 2016-06-15 Bo Zhao , Paola Caselli , Zhi-Yun Li , Ruben Krasnopolsky , Hsien Shang , Fumitaka Nakamura

Magnetic fields play an important role in star formation by regulating the removal of angular momentum from collapsing molecular cloud cores. Hall diffusion is known to be important to the magnetic field behaviour at many of the…

Solar and Stellar Astrophysics · Physics 2011-10-12 Catherine Braiding

The global evolution of protoplanetary disks (PPDs) has recently been shown to be largely controlled by the amount of poloidal magnetic flux threading the disk, which is further controlled by the poorly understood process of magnetic flux…

Earth and Planetary Astrophysics · Physics 2017-02-15 Xue-Ning Bai , James M. Stone

We investigate and discuss protostellar discs in terms of where the various non-ideal magnetohydrodynamics (MHD) processes are important. We find that the traditional picture of a magnetised disc (where Ohmic resistivity is dominant near…

Solar and Stellar Astrophysics · Physics 2021-01-13 James Wurster

Non-ideal magnetohydrodynamic (MHD) processes -- namely Ohmic resistivity, ambipolar diffusion and the Hall effect -- modify the early stages of the star formation process and the surrounding environment. Collectively, they have been shown…

Astrophysics of Galaxies · Physics 2021-08-18 James Wurster , Matthew R. Bate , Ian A. Bonnell

The gas dynamics of protoplanetary disks (PPDs) is largely controlled by non-ideal magnetohydrodynamic (MHD) effects including Ohmic resistivity, the Hall effect and ambipolar diffusion. Among these the role of the Hall effect is the least…

Earth and Planetary Astrophysics · Physics 2015-06-18 Xue-Ning Bai

The role of non-ideal magnetohydrodynamics has been proven critical during the formation of the protoplanetary disk, particularly in regulating its size. We provide a simple model to predict the disk size under the interplay among the…

Earth and Planetary Astrophysics · Physics 2021-11-24 Yueh-Ning Lee , Pierre Marchand , Yu-Hsuan Liu , Patrick Hennebelle

Efficient magnetic braking is a formidable obstacle to the formation of rotationally supported disks (RSDs) around protostars in magnetized dense cores. We have previously shown, through 2D (axisymmetric) non-ideal MHD simulations, that…

Solar and Stellar Astrophysics · Physics 2017-11-17 Bo Zhao , Paola Caselli , Zhi-Yun Li , Ruben Krasnopolsky

We investigate the formation and early evolution of a protostellar disc from a magnetized pre-stellar core using non-ideal magnetohydrodynamic (MHD) simulations including ambipolar diffusion and Ohmic dissipation. The dynamical contraction…

Solar and Stellar Astrophysics · Physics 2021-02-17 Wenrui Xu , Matthew W. Kunz

We use a 3D radiative non-ideal magnetohydrodynamic (MHD) simulation to investigate the formation and evolution of a young protostellar disc from a magnetized pre-stellar core. The simulation covers the first ${\sim}10~{\rm kyr}$ after…

Solar and Stellar Astrophysics · Physics 2021-09-29 Wenrui Xu , Matthew W. Kunz

Protoplanetary discs are poorly ionised due to their low temperatures and high column densities, and are therefore subject to three "non-ideal" magnetohydrodynamic effects: Ohmic dissipation, ambipolar diffusion, and the Hall effect. The…

Solar and Stellar Astrophysics · Physics 2014-07-02 Geoffroy Lesur , Matthew W. Kunz , Sebastien Fromang
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