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Disks are essential to the formation of both stars and planets, but how they form in magnetized molecular cloud cores remains debated. This work focuses on how the disk formation is affected by turbulence and ambipolar diffusion (AD), both…

Solar and Stellar Astrophysics · Physics 2019-09-02 Ka Ho Lam , Zhi-Yun Li , Che-Yu Chen , Kengo Tomida , Bo Zhao

We present the results of a series of time-dependent numerical simulations of cold, magnetocentrifugally launched winds from accretion disks. Our simulations span four and half decades of mass loading; in the context of a disk with a…

Astrophysics · Physics 2009-11-10 Jeffrey M. Anderson , Zhi-Yun Li , Ruben Krasnopolsky , Roger D. Blandford

Large scale magnetic field threading an accretion disk is a key ingredient in the jet formation model. The most attractive scenario for the origin of such a large scale field is the advection of the field by the gas in the accretion disk…

High Energy Astrophysical Phenomena · Physics 2015-06-12 Xinwu Cao , H. C. Spruit

We follow numerically the time evolution of axisymmetric outflows driven magneto-centrifugally from the inner portion of accretion disks, from their launching surface to large, observable distances. Special attention is paid to the…

Astrophysics · Physics 2009-11-10 Ruben Krasnopolsky , Zhi-Yun Li , Roger D. Blandford

We investigate outflows driven by a giant protoplanet using three-dimensional MHD nested grid simulations. We consider a local region around the protoplanet in the protoplanetary disk, and calculate three models: (a) unmagnetized disk…

Astrophysics · Physics 2011-02-11 Masahiro N. Machida , Shu-ichiro Inutsuka , Tomoaki Matsumoto

Using three-dimensional magnetohydrodynamics simulations, the driving of protostellar jets is investigated in different star-forming cores with the parameters of magnetic field strength and mass accretion rate. Powerful high-velocity jets…

Astrophysics of Galaxies · Physics 2021-09-22 Masahiro N. Machida

The formation of high-mass stars is usually accompanied by powerful protostellar outflows. Such high-mass outflows are not simply scaled-up versions of their lower-mass counterparts, since observations suggest that the collimation degree…

Kinematic signatures of the jet, winds, multicavities, and episodic shells arising in the unified model of bipolar outflows developed in Shang et al.\ (2020), in which an outflow forms by radially directed, wide-angle toroidally magnetized…

Solar and Stellar Astrophysics · Physics 2023-03-02 Hsien Shang , Chun-Fan Liu , Ruben Krasnopolsky , Liang-Yao Wang

We have performed a fully three-dimensional general relativistic magnetohydrodynamic (GRMHD) simulation of jet formation from a thin accretion disk around a Schwarzschild black hole with a free-falling corona. The initial simulation results…

This is a doctorate level lecture on the physics of accretion discs driving magnetically self-confined jets, usually referred to in the literature as disc winds. I will first review the governing magnetohydrodynamic equations and then…

Astrophysics · Physics 2008-11-26 Jonathan Ferreira

We numerically investigate the generation of a magnetic field in a protostellar disc via an $\alpha \Omega$-dynamo and the resulting magnetohydrodynamic (MHD) driven outflows. We find that for small values of the dimensionless dynamo…

High Energy Astrophysical Phenomena · Physics 2018-03-05 Sergei Dyda , Richard V. E. Lovelace , Galina V. Ustyugova , Alexander V. Koldoba , Ira Wasserman

We perform a long-term simulation of star and disk formation using three-dimensional non-ideal magnetohydrodynamics. The simulation starts from a prestellar cloud and proceeds through the long-term evolution of the circumstellar disk until…

Solar and Stellar Astrophysics · Physics 2024-05-15 Masahiro N. Machida , Shantanu Basu

Accreting pulsars power relativistic jets, and display a complex spin phenomenology. These behaviours may be closely related to the large-scale configuration of the star's magnetic field, shaped by its interaction with the surrounding…

High Energy Astrophysical Phenomena · Physics 2017-06-21 Kyle Parfrey , Anatoly Spitkovsky , Andrei M. Beloborodov

Short gamma-ray bursts originate when relativistic jets emerge from the remnants of binary neutron star mergers. Both the jet and the remnant are believed to be strongly magnetized, and the presence of magnetic fields is known to influence…

High Energy Astrophysical Phenomena · Physics 2024-11-01 Giancarlo Mattia , Luca Del Zanna , Andrea Pavan , Riccardo Ciolfi

The formation of protostellar disks out of molecular cloud cores is still not fully understood. Under ideal MHD conditions, the removal of angular momentum from the disk progenitor by the typically embedded magnetic field may prevent the…

Astrophysics of Galaxies · Physics 2015-05-30 R. Santos-Lima , E. M. de Gouveia Dal Pino , A. Lazarian

We present numerical magnetohydrodynamic (MHD) simulations of the effect of stellar dipole magnetic fields on line-driven wind outflows from hot, luminous stars. Unlike previous fixed-field analyses, the simulations here take full account…

Astrophysics · Physics 2011-05-05 Asif ud-Doula , Stanley P. Owocki

We report the discovery of propeller-driven outflows in axisymmetric magnetohydrodynamic simulations of disk accretion to rapidly rotating magnetized stars. Matter outflows in a wide cone and is centrifugally ejected from the inner regions…

Astrophysics · Physics 2009-11-13 M. M. Romanova , G. V. Ustyugova , A. V. Koldoba , R. V. E. Lovelace

Hydrodynamic simulations of protoplanetary discs with planets typically assume that the disc is viscously driven, even though magnetic disc winds are now considered the primary driver of angular momentum transport through the disc. Magnetic…

Earth and Planetary Astrophysics · Physics 2025-05-14 Michael Hammer , Min-Kai Lin

We here present the first results of fully three-dimensional (3-D) MHD simulations of radiative cooling pulsed (time-variable) jets for a set of parameters which are suitable for protostellar outflows. Considering different initial magnetic…

Astrophysics · Physics 2009-10-31 Adriano H. Cerqueira , Elisabete M. de Gouveia Dal Pino

The magnetocentrifugal disk wind mechanism is the leading candidate for producing the large-scale, bipolar jets commonly seen in protostellar systems. I present a detailed formulation of a global, radially self-similar model for a non-ideal…

Solar and Stellar Astrophysics · Physics 2015-05-27 Seth Teitler