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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

A non-ideal MHD collapse calculation employing the axisymmetric thin-disk approximation is used to resolve cloud core collapse down to the scales of the second (stellar) core. Rotation and a magnetic braking torque are included in the…

Solar and Stellar Astrophysics · Physics 2013-08-19 Shantanu Basu , Wolf B. Dapp , Matthew W. Kunz

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

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

Disk formation in magnetized cloud cores is hindered by magnetic braking. Previous work has shown that for realistic levels of core magnetization, the magnetic field suppresses the formation of rotationally supported disks during the…

Solar and Stellar Astrophysics · Physics 2010-06-07 Ruben Krasnopolsky , Zhi-Yun Li , Hsien Shang

Magnetic diffusion plays a vital role in star formation. We trace its influence from interstellar cloud scales down to star-disk scales. On both scales, we find that magnetic diffusion can be significantly enhanced by the buildup of strong…

Solar and Stellar Astrophysics · Physics 2013-08-19 Shantanu Basu , Wolf B. Dapp

Magnetic fields are usually considered dynamically important in star formation when the dimensionless mass-to-flux ratio is close to, or less than, unity (lambda<~1). We show that, in disk formation, the requirement is far less stringent.…

Astrophysics · Physics 2009-11-13 Richard R. Mellon , Zhi-Yun Li

The magnetic field plays a central role in the formation and evolution of circumstellar disks. The magnetic field connects the rapidly rotating central region with the outer envelope and extracts angular momentum from the central region…

Solar and Stellar Astrophysics · Physics 2016-03-24 Yusuke Tsukamoto

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

Through the magnetic braking and the launching of protostellar outflows, magnetic fields play a major role in the regulation of angular momentum in star formation, which directly impacts the formation and evolution of protoplanetary disks…

Solar and Stellar Astrophysics · Physics 2020-09-04 Pierre Marchand , Kengo Tomida , Kei Tanaka , Benoît Commerçon , Gilles Chabrier

Truncated abstract: The formation of a protostellar disc is a natural outcome during the star formation process. As gas in a molecular cloud core collapses under self-gravity, the angular momentum of the gas will slow its collapse on small…

Solar and Stellar Astrophysics · Physics 2018-12-18 James Wurster , Zhi-Yun Li

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

We perform axisymmetric resistive MHD calculations that demonstrate that centrifugal disks can indeed form around Class 0 objects despite magnetic braking. We follow the evolution of a prestellar core all the way to near-stellar densities…

Solar and Stellar Astrophysics · Physics 2013-08-19 Wolf B. Dapp , Shantanu Basu

Using resistive magnetohydrodynamics simulation, we investigate circumstellar disk formation in a strongly magnetized cloud. As the initial state, an isolated cloud core embedded in a low-density interstellar medium with a uniform magnetic…

Solar and Stellar Astrophysics · Physics 2015-05-19 Masahiro N. Machida , Shu-ichiro Inutsuka , Tomoaki Matsumoto

The formation of rotationally supported protostellar disks is suppressed in ideal MHD in non-turbulent cores with aligned magnetic field and rotation axis. A promising way to resolve this so-called "magnetic braking catastrophe" is through…

Solar and Stellar Astrophysics · Physics 2015-06-22 Zhi-Yun Li , Ruben Krasnopolsky , Hsien Shang , Bo Zhao

The gas from which stars form is magnetized, and strong magnetic fields can efficiently transport angular momentum. Most theoretical models of this phenomenon find that it should prevent formation of large (>100 AU), rotationally-supported…

Solar and Stellar Astrophysics · Physics 2015-06-12 Mark R. Krumholz , Richard M. Crutcher , Charles L. H. Hull

Recent numerical analysis of Keplerian disk formation in turbulent, magnetized cloud cores by Santos-Lima, de Gouveia Dal Pino, & Lazarian (2012) demonstrated that reconnection diffusion is an efficient process to remove the magnetic flux…

Astrophysics of Galaxies · Physics 2015-06-12 R. Santos-Lima , E. M. de Gouveia Dal Pino , A. Lazarian

We present simulations of collapsing 100 M_\sun mass cores in the context of massive star formation. The effect of variable initial rotational and magnetic energies on the formation of massive stars is studied in detail. We focus on…

Solar and Stellar Astrophysics · Physics 2015-05-28 D. Seifried , R. Banerjee , R. S. Klessen , D. Duffin , R. E. Pudritz

Context: Ideal MHD simulations have revealed catastrophic magnetic braking (MB) in the protostellar phase, which prevents the formation of a centrifugal disk around a nascent protostar. Aims: We determine if non-ideal MHD, including the…

Solar and Stellar Astrophysics · Physics 2013-08-19 Wolf B. Dapp , Shantanu Basu , Matthew W. Kunz
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