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In their early stages, protoplanetary discs are sufficiently massive to undergo gravitational instability (GI). This instability is thought to be involved in mass accretion, planet formation via gas fragmentation, the generation of spiral…

Earth and Planetary Astrophysics · Physics 2021-06-30 A. Riols , W. Xu , G. Lesur , M. W. Kunz , H. Latter

The processes of neutrino (antineutrino) absorption and electron (positron) capture on nucleons provide the dominant mechanisms for heating and cooling the material between the protoneutron star and the stalled shock in a core-collapse…

Astrophysics · Physics 2009-11-10 Huaiyu Duan , Yong-Zhong Qian

The evolution of the magnetic field in an accreting neutron star is investigated using a fully general relativistic treatment and assuming that initially the currents supporting the field are completely confined to the crust. We find that…

Astrophysics · Physics 2009-10-31 Sushan Konar

Solar, stellar and galactic large-scale magnetic fields are originated due to a combined action of non-uniform (differential) rotation and helical motions of plasma via mean-field dynamos. Usually, nonlinear mean-field dynamo theories take…

Solar and Stellar Astrophysics · Physics 2024-04-19 I. Rogachevskii , N. Kleeorin

According to our understanding of stellar evolution, early-type stars have radiative envelopes and convective cores due to a steep temperature gradient produced by the CNO cycle. Some of these stars (mainly, the subclasses Ap and Bp) have…

Solar and Stellar Astrophysics · Physics 2023-03-21 J. P. Hidalgo , P. J. Käpylä , C. A. Ortiz-Rodríguez , F. H. Navarrete , B. Toro , D. R. G. Schleicher

Via amplification by turbulent dynamo, magnetic fields can be potentially important for the formation of the first stars. To examine the dynamo behavior during the gravitational collapse of primordial gas, we extend the theory of nonlinear…

Solar and Stellar Astrophysics · Physics 2020-08-26 Siyao Xu , Alex Lazarian

We study the stability/establishment of dipolar magnetostatic equilibrium configurations in new--born neutron stars (NSs) in dependence on the rotational velocity $\Omega$ and on the initial angle $\alpha$ between rotation and magnetic…

Astrophysics · Physics 2009-11-11 U. Geppert , M. Rheinhardt

Neutron stars are the endpoint of the life of intermediate mass stars and posses in their cores matter in the most extreme conditions in the universe. Besides their extremes of temperature (found in proto-neutron stars) and densities,…

High Energy Astrophysical Phenomena · Physics 2018-06-07 R. O. Gomes , S. Schramm , V. Dexheimer

Neutron stars contain the strongest magnetic fields known in the Universe. In this paper, I discuss briefly how these magnetic fields are inferred from observations, as well as the evidence for their time-evolution. I show how these…

Solar and Stellar Astrophysics · Physics 2013-05-14 Andreas Reisenegger

Well before the radio discovery of pulsars offered the first observational confirmation for their existence (Hewish et al., 1968), it had been suggested that neutron stars might be endowed with very strong magnetic fields of…

High Energy Astrophysical Phenomena · Physics 2019-02-18 Konstantinos N. Gourgouliatos , Paolo Esposito

Aims. We investigate the cosmological evolution of large- and small-scale magnetic fields in galaxies in the light of present models of formation and evolution of galaxies. Methods. We use the dynamo theory to derive the timescales of…

Astrophysics · Physics 2009-11-13 Tigran G. Arshakian , Rainer Beck , Marita Krause , Dmitry Sokoloff

The Sun and other cool stars harbouring outer convection zones manifest magnetic activity in their atmospheres. The connection between this activity and the properties of a deep-seated dynamo generating the magnetic flux is not well…

Solar and Stellar Astrophysics · Physics 2015-05-27 Emre Işık , Dieter Schmitt , Manfred Schüssler

In the mean field approximation of the relativistic $\sigma$-$\omega$-$\rho$ model, the magnetic fields are incorporated, and its influence on the properties of n-p-e neutron star matter are studied. When the strength of the magnetic field…

Astrophysics · Physics 2008-11-26 W. Chen , P. Q. Zhang , L. G. Liu

Magnetic field amplification by a fast dynamo is seen in local box simulations of SN-driven ISM turbulence, where the self-consistent emergence of large-scale fields agrees very well with its mean-field description. We accordingly derive…

Cosmology and Nongalactic Astrophysics · Physics 2012-06-25 Detlef Elstner , Oliver Gressel

Dynamical mean field theory (DMFT) is used to study neutron matter, both with and without admixture of the proton fraction. The system is approximated by the lattice Habbard model. The corresponding equation of state as a function of…

Strongly Correlated Electrons · Physics 2021-05-26 Maxim Velikanov , Alexey N. Rubtsov , Boris Krippa

In this paper we show that the Universe is already strongly magnetized at very early epochs during cosmic evolution. Our calculations are based on the efficient amplification of weak magnetic seed fields, which are unavoidably present in…

Cosmology and Nongalactic Astrophysics · Physics 2014-05-09 Jacques M. Wagstaff , Robi Banerjee , Dominik Schleicher , Guenter Sigl

(Abridged) The rotational evolution of isolated neutron stars is dominated by the magnetic field anchored to the solid crust of the star. Assuming that the core field evolves on much longer timescales, the crustal field evolves mainly…

Solar and Stellar Astrophysics · Physics 2013-06-11 Jose A. Pons , Daniele Vigano , Ulrich Geppert

A phase transition from paramagnetism to ferromagnetism in neutron star interior is explored. Since there is $^3$P$_2$ neutron superfluid in neutron star interior, it can be treated as a system of magnetic dipoles. Under the presence of…

High Energy Astrophysical Phenomena · Physics 2009-11-12 Qiu He Peng , Hao Tong

Magnetic fields are ubiquitous in the Universe. Extragalactic disks, halos and clusters have consistently been shown, via diffuse radio-synchrotron emission and Faraday rotation measurements, to exhibit magnetic field strengths ranging from…

Core convection and dynamo activity deep within rotating A-type stars of 2 solar masses are studied with 3--D nonlinear simulations. Our modeling considers the inner 30% by radius of such stars, thus capturing within a spherical domain the…

Astrophysics · Physics 2008-11-26 Allan Sacha Brun , Matthew K. Browning , Juri Toomre