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Related papers: Planetary dynamos driven by semiconvection in stab…

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Regions of stellar and planetary interiors that are unstable according to the Schwarzschild criterion, but stable according to the Ledoux criterion, are subject to a form of oscillatory double-diffusive (ODD) convection often called…

Solar and Stellar Astrophysics · Physics 2015-01-22 Toby S. Wood , Pascale Garaud , Stephan Stellmach

We find an instability resulting in generation of large-scale vorticity in a fast rotating small-scale turbulence or turbulent convection with inhomogeneous fluid density along the rotational axis in anelastic approximation. The large-scale…

Fluid Dynamics · Physics 2019-12-11 Igor Rogachevskii , Nathan Kleeorin

A series of numerical simulations of the dynamo process operating inside gas giant planets has been performed. We use an anelastic, fully nonlinear, three-dimensional, benchmarked MHD code to evolve the flow, entropy and magnetic field. Our…

Earth and Planetary Astrophysics · Physics 2018-01-11 Wieland Dietrich , Chris. A. Jones

The magnetic fields of spiral galaxies are so strong that they cannot be primordial. Their typical values are over one billion times higher than any value predicted for the early Universe. Explaining this immense growth and incorporating it…

Astrophysics of Galaxies · Physics 2020-09-30 Evangelia Ntormousi , Konstantinos Tassis , Fabio Del Sordo , Francesca Fragkoudi , Rüdiger Pakmor

In an atmosphere, a cloud condensation region is characterized by a strong vertical gradient in the abundance of the related condensing species. On Earth, the ensuing gradient of mean molecular weight has relatively few dynamical…

Earth and Planetary Astrophysics · Physics 2017-02-08 Jérémy Leconte , Franck Selsis , Franck Hersant , Tristan Guillot

The current dynamo paradigm for the Sun and sun-like stars places the generation site for strong toroidal magnetic structures deep in the solar interior. Sunspots and star-spots on sun-like stars are believed to arise when sections of these…

Solar and Stellar Astrophysics · Physics 2015-05-30 Nicholas J. Nelson , Benjamin P. Brown , Allan Sacha Brun , Mark S. Miesch , Juri Toomre

In solar-type stars (with radiative cores and convective envelopes), the magnetic field powers star spots, flares and other solar phenomena, as well as chromospheric and coronal emission at ultraviolet to X-ray wavelengths. The dynamo…

Solar and Stellar Astrophysics · Physics 2016-08-17 Nicholas J. Wright , Jeremy J. Drake

We consider generation and evolution of small-scale magnetic fields in neutron stars. These fields can be generated by small-scale turbulent dynamo action soon after the collapse when the proto-neutron star is subject to convective and…

Astrophysics · Physics 2009-11-10 V. Urpin , J. Gil

Thermal convection in fluid layers heated from below are usually realized experimentally as well as treated theoretically with fixed boundaries on which conditions for the temperature and the velocity field are prescribed. The thermal and…

Fluid Dynamics · Physics 2011-02-08 R. D. Simitev , F. H. Busse

The convective envelopes of cool main-sequence stars harbour magnetic fields with a complex global and local structure. These fields affect the near-surface convection and the outer stellar atmospheres in many ways and are responsible for…

Solar and Stellar Astrophysics · Physics 2015-09-02 Benjamin Beeck , Manfred Schüssler , Robert H. Cameron , Ansgar Reiners

Context. Red-giant stars may engulf planets. This may increase the rotation rate of their convective envelope, which could lead to strong dynamo-triggered magnetic fields. Aims. We explore the possibility of generating magnetic fields in…

Planetary and stellar magnetic fields are thought to be sustained by helical motions ($\alpha$-effect) and, if present, differential rotation ($\Omega$-effect). In the Sun, the strong differential rotation in the tachocline is responsible…

Earth and Planetary Astrophysics · Physics 2014-02-04 Wieland Dietrich , Dieter Schmitt , Johannes Wicht

We present a combined model for magnetic field generation and transport in cool stars with outer convection zones. The mean toroidal magnetic field, which is generated by a cyclic thin-layer alpha-omega dynamo at the bottom of the…

Solar and Stellar Astrophysics · Physics 2011-11-11 Emre Işık , Dieter Schmitt , Manfred Schüssler

In this manuscript using the asymptotic method of multiscale nonlinear theory we construct a nonlinear theory of the appearance of large-scale structures in the stratified conductive medium with the presence of small-scale oscillations of…

Earth and Planetary Astrophysics · Physics 2016-12-30 M. I. Kopp , A. V. Tur , V. V. Yanovsky

M-dwarf stars are well known for the intense magnetic activity that many of them exhibit. In cool stars with near-surface convection zones, this magnetic activity is thought to be driven largely by the interplay of convection and the large…

Solar and Stellar Astrophysics · Physics 2022-03-30 Connor P. Bice , Juri Toomre

In the quiet Sun, magnetic fields are usually observed as small-scale magnetic elements, `salt and pepper', covering the entire solar surface. By using 3D radiative MHD numerical simulations we demonstrate that these fields are a result of…

Solar and Stellar Astrophysics · Physics 2013-12-05 I. N. Kitiashvili , A. G. Kosovichev , N. N. Mansour , A. A. Wray

Spiral galaxies, including the Milky Way, have large-scale magnetic fields with significant energy densities. The dominant theory attributes these magnetic fields to a large-scale dynamo. We review the current status of dynamo theory and…

Astrophysics of Galaxies · Physics 2023-08-31 Axel Brandenburg , Evangelia Ntormousi

Coupled mixed convective and stratified systems are common in natural flows. To study experimentally the associated dynamics, we use a singular property of water: its non-linear equation of state is characterised by a maximum density close…

Fluid Dynamics · Physics 2020-11-10 Pierre Léard , Benjamin Favier , Patrice Le Gal , Michael Le Bars

The property of inhomogeneous turbulence in conducting fluids to expel large-scale magnetic fields in the direction of decreasing turbulence intensity is shown as important for the magnetic field dynamics near the base of a stellar…

Astrophysics · Physics 2009-11-13 L. L. Kitchatinov , G. Rüdiger

For a long time, gravitational instability in the disk of planetesimals has been suspected to be the main engine responsible for the beginning of dust growth, its advantage being that it provides for rapid growth. Its real importance in…

Astrophysics · Physics 2009-11-10 P. Tanga , S. J. Weidenschilling , P. Michel , D. C. Richardson