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Numerical experiments have been performed to investigate the thermal behavior of a cooled down white dwarf of initial mass $M_{\rm WD} = 0.516 M_{\sun}$ which accretes hydrogen-rich matter with Z = 0.02 at the rate $\dot{M}=10^{-8}$ \msun…

Astrophysics · Physics 2009-10-31 L. Piersanti , S. Cassisi , I. Iben , A. Tornambe'

Advanced 3D radiative MHD simulations now reproduce many properties of the outer solar atmosphere. When including a domain from the convection zone into the corona, a hot chromosphere and corona are self-consistently maintained. Here we…

Solar and Stellar Astrophysics · Physics 2015-10-07 Viggo Hansteen , Nuno Guerreiro , Bart De Pontieu , Mats Carlsson

Density functional calculations of electronic structure, total energy, structural distortions, and magnetism for hydrogenated single-layer, bilayer, and multi-layer graphene are performed. It is found that hydrogen-induced magnetism can…

Materials Science · Physics 2008-01-24 D. W. Boukhvalov , M. I. Katsnelson , A. I. Lichtenstein

We assess the partition function and ionization degree of magnetized hydrogen atoms at thermodynamic equilibrium for a wide range of field intensities, $B\approx 10^5$-$10^{12}$~G. Evaluations include fitting formulae for an arbitrary…

Solar and Stellar Astrophysics · Physics 2020-04-01 Matías Vera Rueda , René D. Rohrmann

Because of their activity, late-type stars are known to host powerful flares producing intense high-energy radiation on short time-scales that may significantly affect the atmosphere of nearby planets. We employ a one-dimensional aeronomic…

Earth and Planetary Astrophysics · Physics 2018-12-26 D. V. Bisikalo , V. I. Shematovich , A. A. Cherenkov , L. Fossati , C. Moestl

We use axisymmetric magnetohydrodynamic simulations to investigate the spinning-down of magnetars rotating in the propeller regime and moving supersonically through the interstellar medium. The simulations indicate that magnetars spin-down…

Astrophysics · Physics 2009-11-11 O. D. Toropina , M. M. Romanova , R. V. Lovelace

Magnetars are neutron stars characterized by strong surface magnetic fields generally exceeding the quantum critical value of 44.1 TeraGauss. High-energy photons propagating in their magnetospheres can be attenuated by QED processes like…

High Energy Astrophysical Phenomena · Physics 2022-11-30 Kun Hu , Matthew G. Baring , Alice K. Harding , Zorawar Wadiasingh

We investigate the role of non-thermal electrons in the formation regions of Halpha, Hbeta, and Hgamma lines in order to unfold their influence on the formation of these lines. We concentrate on pulse-beam heating varying on a subsecond…

Solar and Stellar Astrophysics · Physics 2015-05-13 J. Kasparova , M. Varady , P. Heinzel , M. Karlicky , Z. Moravec

Solar flares are known to be prolific electron accelerators, yet identifying the mechanism(s) for such efficient electron acceleration in solar flare (and similar astrophysical settings) presents a major challenge. This is due in part to a…

Solar and Stellar Astrophysics · Physics 2023-04-18 Eduard P. Kontar , A. Gordon Emslie , Galina G. Motorina , Brian R. Dennis

In order to investigate the anomalous heat effect (AHE) in NiCu multilayer thin film, photon radiation calorimetry has been developed. Three types of photon detectors are employed to cover a wide range of wavelengths from 0.3 um to 5.5 um,…

Instrumentation and Detectors · Physics 2024-10-01 J. Kasagi , T. Itoh , Y. Shibasaki , T. Takahashi , S. Yamauchi , Y. Iwamura

Models and simulations of the epoch of reionization predict that spectra of the 21-cm transition of atomic hydrogen will show a clear fluctuation peak, at a redshift and scale, respectively, that mark the central stage of reionization and…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-18 Anastasia Fialkov , Rennan Barkana , Eli Visbal

Magnetic reconnection in strongly magnetized (low-beta), weakly collisional plasmas is investigated using a novel fluid-kinetic model [Zocco & Schekochihin, Phys. Plasmas 18, 102309 (2011)] which retains non-isothermal electron kinetics. It…

Plasma Physics · Physics 2015-06-12 N. F. Loureiro , A. A. Schekochihin , A. Zocco

The photospheric emission in the prompt phase is the natural prediction of the original fireball model for gamma-ray burst (GRB) due to the large optical depth ($\tau >1$) at the base of the outflow, which is supported by the quasi-thermal…

High Energy Astrophysical Phenomena · Physics 2021-12-02 Yan-Zhi Meng , Jin-Jun Geng , Xue-Feng Wu

Deciphering and understanding the small-scale magnetic activity of the quiet solar photosphere should help to solve many of the key problems of solar and stellar physics, such as the magnetic coupling to the outer atmosphere and the coronal…

Astrophysics · Physics 2007-05-23 J. Trujillo Bueno , N. Shchukina , A. Asensio Ramos

The dissipation of intense crustal electric currents produces high Joule heating rates in cooling neutron stars. Here it is shown that Joule heating can counterbalance fast cooling, making it difficult to infer the presence of hyperons…

High Energy Astrophysical Phenomena · Physics 2022-05-31 F. Anzuini , A. Melatos , C. Dehman , D. Viganò , J. A. Pons

We construct models for strongly-magnetized neutron star atmospheres composed of mid-Z elements (carbon, oxygen and neon) with magnetic fields B=10^{12}-10^{13} G and effective temperatures Teff=(1-5)*10^6 K; this is done by first…

Astrophysics · Physics 2008-11-26 Kaya Mori , Wynn C. G. Ho

Investigate particle acceleration and heating in a solar microflare. In a microflare with non-thermal emission to remarkably high energies ($>50$ keV), we investigate the hard X-rays with RHESSI imaging and spectroscopy and the resulting…

Astrophysics · Physics 2010-09-17 I. G. Hannah , S. Krucker , H. S. Hudson , S. Christe , R. P. Lin

The accretion flow within the magnetospheric radius of bright X-ray pulsars can form an optically thick envelope, concealing the central neutron star from the distant observer. Most photons are emitted at the surface of a neutron star and…

High Energy Astrophysical Phenomena · Physics 2024-03-13 Caitlyn Flexer , Alexander A. Mushtukov

We present the first vertically resolved hydrodynamic simulations of a laterally propagating, deflagrating flame in the thin helium ocean of a rotating accreting neutron star. We use a new hydrodynamics solver tailored to deal with the…

High Energy Astrophysical Phenomena · Physics 2015-06-12 Yuri Cavecchi , Anna L. Watts , Jonathan Braithwaite , Yuri Levin

High-pressure metal-hydride (MH) research evolved into a thriving field within condensed matter physics following the realisation of metallic compounds showing phonon mediated near room-temperature superconductivity. However, severe…

Materials Science · Physics 2022-08-09 Thomas Meier , Dominique Laniel , Florian Trybel