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Planetary and stellar dynamos likely result from turbulent motions in magnetofluids with kinematic viscosities that are small compared to their magnetic diffusivities. Laboratory experiments are in progress to produce similar dynamos in…

Astrophysics · Physics 2009-11-11 P. D. Mininni

Supersonic turbulent motions are the remarkable properties of interstellar medium. Previous numerical simulations have demonstrated that the thermal instability in a shock-compressed layer produces the supersonic turbulent motion that does…

Astrophysics · Physics 2007-05-23 Hiroshi Koyama , Shu-ichiro Inutsuka

We use three-dimensional hydrodynamic numerical simulations to study phase transformations occurring in a clumpy interstellar gas exposed to time-dependent volumetric heating. To mimic conditions in the Galactic interstellar medium, we take…

Astrophysics · Physics 2009-11-07 Alexei G. Kritsuk , Michael L. Norman

Flows are omnipresent and govern the dynamics of plasma. Solar tornadoes are a class of apparently rotating prominences, that might be formed by thermal instability. In spectroscopic studies on thermal instability background flow is…

Solar and Stellar Astrophysics · Physics 2024-06-12 Joris Hermans , Rony Keppens

In many astrophysical environments, self-gravity can generate kinetic energy, which, in principle, is available for driving dynamo action. Using direct numerical simulations, we show that in unstirred self-gravitating subsonic turbulence…

Astrophysics of Galaxies · Physics 2022-04-20 Axel Brandenburg , Evangelia Ntormousi

We have investigated steady, radial gas outflows (or winds) from galaxies and the development of thermal instability in the hot gas. In order to see the maximum influence of the instability on the global structure of the galactic outflows,…

Astrophysics · Physics 2009-10-31 Yutaka Fujita

In this work, we explore the link between star formation, turbulence and the thermal state of the multi-phase ISM. We analyse a suite of stratified box simulations modelling a realistic ISM that aims to probe environments similar to those…

In this paper, the nonlinear evolution of a bistable interstellar medium is investigated using two-dimensional simulations with a realistic cooling rate, thermal conduction, and physical viscosity. The calculations are performed using…

Astrophysics of Galaxies · Physics 2015-06-17 Kazunari Iwasaki , Shu-ichiro Inutsuka

Thermally bistable fluid tends to self-organize into clouds of hot and cold material, which are internally uniform and separated by thin conduction fronts. The evolution of these clouds has been studied for isobaric systems, but when…

Plasma Physics · Physics 2024-07-18 Henry Fetsch , Nathaniel J. Fisch

We study the interplay among cooling, heating, conduction, and magnetic fields in gravitationally stratified plasmas using simplified, plane-parallel numerical simulations. Since the physical heating mechanism remains uncertain in massive…

Cosmology and Nongalactic Astrophysics · Physics 2012-12-05 Michael McCourt , Prateek Sharma , Eliot Quataert , Ian J. Parrish

The turbulent dynamo may explain the origin of cosmic magnetism. While the exponential amplification of magnetic fields has been studied for incompressible gases, little is known about dynamo action in highly-compressible, supersonic…

Astrophysics of Galaxies · Physics 2014-12-05 Christoph Federrath , Jennifer Schober , Stefano Bovino , Dominik R. G. Schleicher

We study the dynamo instability driven by a turbulent two dimensional flow with three components of the form (u(x, y, t), v(x, y, t), w(x, y, t)) sometimes referred to as a 2.5 dimensional flow. This type of flows provides an approximation…

Fluid Dynamics · Physics 2016-08-24 K. Seshasayanan , A. Alexakis

Magnetic fields can be created in stably stratified (non-convective) layers in a differentially rotating star. A magnetic instability in the toroidal field (wound up by differential rotation) replaces the role of convection in closing the…

Astrophysics · Physics 2009-11-07 H. C. Spruit

Turbulence in the intracluster medium (ICM) is driven by active galactic nuclei (AGNs) jets, by mergers, and in the wakes of infalling galaxies. It not only governs gas motion but also plays a key role in the ICM thermodynamics. Turbulence…

Astrophysics of Galaxies · Physics 2021-12-10 Rajsekhar Mohapatra , Mrinal Jetti , Prateek Sharma , Christoph Federrath

(Abridged) We discuss the nonlinear development of the isobaric mode of thermal instability (TI) in the context of the atomic interstellar medium (ISM), in order to assess the ability of TI to establish a well-segregated multi-phase…

Astrophysics · Physics 2009-11-07 F. J. Sanchez-Salcedo , E. Vazquez-Semadeni , A. Gazol

Thermal instability is one of the most important processes in the formation of clumpy substructure in magnetic molecular clouds. On the other hand, ambipolar diffusion, or ion-neutral friction, has long been thought to be an important…

Astrophysics · Physics 2009-11-10 Mohsen Nejad-Asghar , Jamshid Ghanbari

Turbulence is ubiquitous in the insterstellar medium and plays a major role in several processes such as the formation of dense structures and stars, the stability of molecular clouds, the amplification of magnetic fields, and the…

Astrophysics of Galaxies · Physics 2015-06-19 D. Falceta-Goncalves , G. Kowal , E. Falgarone , A. C. -L. Chian

The role of turbulence in various astrophysical settings is reviewed. Among the differences to laboratory and atmospheric turbulence we highlight the ubiquitous presence of magnetic fields that are generally produced and maintained by…

Solar and Stellar Astrophysics · Physics 2015-03-13 Axel Brandenburg , Aake Nordlund

Depending on the involved physiobiological parameters, stable or unstable behavior in active fluids is observed. In this paper a rigorous analytical justification of (in-)stability within the corresponding regimes is given. In particular,…

Analysis of PDEs · Mathematics 2023-08-03 Christiane Bui , Christian Gesse , Jürgen Saal

Radiative shock waves show a strong cooling instability at temperatures above approximately 2 times 10^5 K. We numerically investigate this instability by simulating different astronomical objects in which colliding flows play an…

Astrophysics · Physics 2008-02-03 Rolf Walder , Doris Folini