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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 seismological dynamics of magnetars is largely determined by a strong hydro-magnetic coupling between the solid crust and the fluid core. In this paper we set up a "spectral" computational framework in which the magnetar's motion is…

High Energy Astrophysical Phenomena · Physics 2015-05-30 Maarten van Hoven , Yuri Levin

Using viscoelastic mass spring model simulations to track heat distribution inside a tidally perturbed body, we measure the asymmetry of heating in the crust of a spin synchronous Moon in eccentric orbit about the Earth. With the Moon…

Earth and Planetary Astrophysics · Physics 2019-05-01 Alice C. Quillen , Larkin Martini , Miki Nakajima

Mercury's crust has a complex structure resulting from a billion years of volcanism. The surface variations in chemical composition have been identified from orbit by the spacecraft MESSENGER. Combining these measurements with laboratory…

Earth and Planetary Astrophysics · Physics 2020-12-01 Mikael Beuthe , Bernard Charlier , Olivier Namur , Attilio Rivoldini , Tim Van Hoolst

The excitation and further sustenance of large-scale magnetic fields in rotating astrophysical systems, including planets, stars and galaxies, is generally thought to involve a fluid magnetic dynamo effect driven by helical…

Fluid Dynamics · Physics 2021-12-10 F. Rincon

Despite heat flux's role in regulating energy conversion in collisionless plasmas, its properties and evolution in the magnetosheath downstream of the Earth's bow shock are scarcely explored. We use MMS in situ measurements to quantify and…

The dynamo mechanism, responsible for the solar magnetic activity, is still an open problem in astrophysics. Different theories proposed to explain such phenomena have failed in reproducing the observational properties of the solar…

Solar and Stellar Astrophysics · Physics 2020-09-30 G Guerrero

Context: Large-scale magnetic fields resulting from hydromagnetic dynamo action may differ substantially in their time dependence. Cyclic field variations, characteristic for the solar magnetic field, are often explained by an important…

Solar and Stellar Astrophysics · Physics 2015-05-27 M. Schrinner , L. Petitdemange , E. Dormy

We explore the influence of geometry variations on the structure and the time-dependence of the magnetic field that is induced by kinematic $\alpha^{2}$ dynamos in a finite cylinder. The dynamo action is due to an anisotropic $\alpha$…

Geophysics · Physics 2009-05-12 R. Avalos-Zuñiga , M. Xu , F. Stefani , G. Gerbeth , F. Plunian

Airborne dust is the main climatic agent in the Martian environment. Local dust storms play a key role in the dust cycle; yet their life cycle is poorly known. Here we use mesoscale modeling that includes the transport of radiatively active…

Earth and Planetary Astrophysics · Physics 2013-05-21 Aymeric Spiga , Julien Faure , Jean-Baptiste Madeleine , Anni Määttänen , François Forget

Convection in the liquid outer core of the Earth is driven by thermal and chemical perturbations. The main purpose of this study is to examine the impact of double-diffusive convection on magnetic field generation by means of 3D global…

Geophysics · Physics 2021-05-12 Théo Tassin , Thomas Gastine , Alexandre Fournier

We employ the MarsWRF general circulation model (GCM) to test the predictions of a new physical hypothesis: a weak coupling of the orbital and rotational angular momenta of extended bodies is predicted to give rise to cycles of…

Earth and Planetary Astrophysics · Physics 2017-05-24 Michael A. Mischna , James H. Shirley

Differential rotation in stars generates toroidal magnetic fields whenever an initial seed poloidal field is present. The resulting magnetic stresses, along with viscosity, drive the star toward uniform rotation. This magnetic braking has…

Astrophysics · Physics 2009-11-10 James N. Cook , Stuart L. Shapiro , Branson C. Stephens

Meridional flow results from slight deviations from the thermal wind balance. The deviations are relatively large in the boundary layers near the top and bottom of the convection zone. Accordingly, the meridional flow attains its largest…

Solar and Stellar Astrophysics · Physics 2015-06-11 Leonid L. Kitchatinov

The generation of solar non-axisymmetric magnetic fields is studied based on a linear alpha2-Omega dynamo model in a rotating spherical frame. The model consists of a solar-like differential rotation, a magnetic diffusivity varied with…

Astrophysics · Physics 2008-11-26 Jie Jiang , Jingxiu Wang

Through the process of thermal ionization, intense stellar irradiation renders Hot Jupiter atmospheres electrically conductive. Simultaneously, lateral variability in the irradiation drives the global circulation with peak wind speeds of…

Earth and Planetary Astrophysics · Physics 2015-06-16 Konstantin Batygin , Sabine Stanley , David J. Stevenson

In a rigidly-rotating magnetohydrodynamic (MHD) system with convective turbulence, a large-scale dynamo, categorized as the $\alpha^2$-type, can be excited when the spin rate is large enough. In this paper, the rotational dependence of the…

Solar and Stellar Astrophysics · Physics 2022-06-15 Youhei Masada , Takayoshi Sano

Magnetic braking causes the spin-down of single stars as they evolve on the main sequence. Models of magnetic braking can also explain the evolution of close binary systems, including cataclysmic variables. The well-known period gap in the…

Solar and Stellar Astrophysics · Physics 2012-02-24 G. A. J. Hussain

We use Mars Atmosphere and Volatile EvolutioN observations of the upstream solar wind, and Mars Express observations of ionospheric electron densities and magnetic fields, to study how the topside ionosphere ($>$ 320 km) of Mars is affected…

Space Physics · Physics 2019-08-02 Z. Girazian , J. Halekas , D. D. Morgan , A. J. Kopf , D. A. Gurnett , F. Chu

The mechanism of large-scale dynamos in rigidly rotating stratified convection is explored by direct numerical simulations (DNS) in Cartesian geometry. A mean-field dynamo model is also constructed using turbulent velocity profiles…

Solar and Stellar Astrophysics · Physics 2015-06-22 Youhei Masada , Takayoshi Sano