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Dynamical collapses of magnetized molecular cloud cores are studied with magnetohydrodynamical simulations from the run-away collapse phase to the accretion phase. In the run-away collapse phase, a disk threaded by magnetic field lines is…

Astrophysics · Physics 2009-10-30 Kohji Tomisaka

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

The problem of the stability of magnetic fields in stars has a long history and has been investigated in detail in perturbation theory. Here we consider the nonlinear evolution of a non-rotating neutron star with a purely poloidal magnetic…

General Relativity and Quantum Cosmology · Physics 2015-03-19 Riccardo Ciolfi , Samuel K. Lander , Gian Mario Manca , Luciano Rezzolla

We present new generation mechanisms of magnetic fields in supernova remnant shocks propagating to partially ionized plasmas in the early universe. Upstream plasmas are dissipated at the collisionless shock, but hydrogen atoms are not…

High Energy Astrophysical Phenomena · Physics 2022-09-08 Shuhei Kashiwamura , Yutaka Ohira

We investigate the generation of magnetic fields above black hole accretion discs due to the non-zero curl of the disc radiation field. By self consistently computing the components of the radiation flux and their curl, we show that the…

High Energy Astrophysical Phenomena · Physics 2025-05-16 Mukesh Kumar Vyas , Asaf Pe'er

In [Gusakov et al.\ PRD, 96, 103012, (2017)], we proposed a self-consistent method to study the quasistationary evolution of the magnetic field in neutron-star cores. Here we apply it to calculate the instantaneous particle velocities and…

High Energy Astrophysical Phenomena · Physics 2018-08-13 D. D. Ofengeim , M. E. Gusakov

Supernova Remnants (SNRs) shocks are believed to accelerate charged particles and to generate strong turbulence in the post-shock flow. From high-energy observations in the past decade, a magnetic field at SNR shocks largely exceeding the…

High Energy Astrophysical Phenomena · Physics 2015-06-18 F. Fraschetti

We review theoretical models of the early stages of star formation, in which gravitational collapse is strongly regulated by magnetic fields and the associated process of ambipolar diffusion. We discuss results of numerical simulations and…

Astrophysics · Physics 2007-05-23 Glenn E. Ciolek , Shantanu Basu

Galactic cosmic rays are believed to be mostly accelerated at supernova shocks. However, the interstellar magnetic field is too weak to efficiently accelerate galactic cosmic rays up to the highest energies, i.e. $10^{15}$ eV. A stronger…

High Energy Astrophysical Phenomena · Physics 2016-03-16 Maria Victoria del Valle , Alexandre Lazarian , Reinaldo Santos-Lima

We investigate the observability, by direct and indirect means, of a shock precursor arising from magnetic field amplification by cosmic rays. We estimate the depth of such a precursor under conditions of nonresonant amplification, which…

High Energy Astrophysical Phenomena · Physics 2015-06-19 J. Martin Laming , Una Hwang , Parviz Ghavamian , Cara Rakowski

Magnetic configurations, stable on the long term, appear to exist in various evolutionary phases, from Main-Sequence stars to white dwarfs and neutron stars. The large scale ordered nature of these fields, often approximately dipolar, and…

Solar and Stellar Astrophysics · Physics 2015-06-22 Andre Maeder , Georges Meynet

Zeeman-Doppler imaging studies have revealed the complexity of the large-scale magnetic fields of accreting pre-main-sequence stars. All have multipolar magnetic fields with the octupole component being the dominant field mode for many of…

Solar and Stellar Astrophysics · Physics 2016-09-02 Scott G. Gregory , Jean-François Donati , Gaitee A. J. Hussain

Magnetic field-aligned electric fields are characteristic features of magnetic reconnection processes operating in externally agitated magnetized plasmas. An especially interesting environment for such a process are the coronae of accretion…

Astrophysics · Physics 2011-05-23 R. Schopper , H. Lesch , G. T. Birk

It is shown that amplification of the magnetic field in supernova remnants (SNRs) occurs in all six objects where morphological measurements are presently available in the hard X-ray continuum at several keV. For the three archetypical…

Astrophysics · Physics 2008-11-26 H. J. Voelk , E. G. Berezhko , L. T. Ksenofontov

Magnetic fields in galaxies are believed to be the result of dynamo amplification of initially weak seed fields, reaching equipartition strength inside the interstellar medium. The small-scale dynamo appears to be a viable mechanism to…

Astrophysics of Galaxies · Physics 2017-08-16 Michael Rieder , Romain Teyssier

We present self-similar solutions that describe the gravitational collapse of rotating, isothermal, magnetic molecular-cloud cores, relevant to the formation of rotationally supported protostellar disks. This work focuses on the evolution…

Astrophysics · Physics 2009-11-07 Ruben Krasnopolsky , Arieh Konigl

Current models of magnetars require extremely strong magnetic fields to explain their observed quiescent and bursting emission, implying that the field strength within the star's outer crust is orders of magnitude larger than the dipole…

Solar and Stellar Astrophysics · Physics 2016-04-07 Konstantinos N. Gourgouliatos , Toby Wood , Rainer Hollerbach

The acceleration of cosmic rays up to PeV energies at supernova remnant shocks requires an amplification of the ambient magnetic field. The amplification mechanism must operate upstream of the shock, to prevent the escape of particles from…

High Energy Astrophysical Phenomena · Physics 2026-04-21 S. Gabici , J. C. Raymond , A. Ciardi , P. Cristofari , S. Recchia , V. Tatischeff

Stars form in dense cores of magnetized molecular clouds. If the magnetic flux threading the cores is dragged into the stars, the stellar field would be orders of magnitude stronger than observed. This well-known "magnetic flux problem"…

Solar and Stellar Astrophysics · Physics 2015-05-28 Bo Zhao , Zhi-Yun Li , Fumitaka Nakamura , Ruben Krasnopolsky , Hsien Shang

Building on our previous hydrodynamic study of the angular momenta of cloud cores formed during gravitational collapse of star-forming molecular gas in our previous work, we now examine core properties assuming ideal magnetohydrodynamics…

Solar and Stellar Astrophysics · Physics 2020-04-29 Aleksandra Kuznetsova , Lee Hartmann , Fabian Heitsch