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We investigate the properties of highly compressible turbulence, the compressibility arising from a small effective polytropic exponent $\gamma_e$ due to cooling. In the limit of small $\gamma_e$, the density jump at shocks is shown to be…

Astrophysics · Physics 2009-10-28 E. Vazquez-Semadeni , T. Passot , A. Pouquet

How molecular clouds fragment and create the dense structures which go on to form stars is an open question. We investigate the relative importance of different energy terms (kinetic, thermal, magnetic, and gravity - both self-gravity and…

Astrophysics of Galaxies · Physics 2022-04-07 S. Ganguly , S. Walch , S. D. Clarke , D. Seifried

We simulate the collapse of a turbulent gas cloud with the particle-based code Gadget2. We choose two sub-clouds, formed by those particles located around the centers $\vec{r}_L$ and $\vec{r}_R$ and within the radii $r_L$ and $r_R$,…

Solar and Stellar Astrophysics · Physics 2022-10-12 Guillermo Arreaga-Garcia

Cold, non-self-gravitating clumps occur in various astrophysical systems, ranging from the interstellar and circumgalactic medium (CGM), to AGN outflows and solar coronal loops. Cold gas has diverse origins such as turbulent mixing or…

Astrophysics of Galaxies · Physics 2021-12-23 Alankar Dutta , Prateek Sharma , Dylan Nelson

{It has recently been proposed that giant molecular complexes form at the sites where streams of diffuse warm atomic gas collide at transonic velocities.} {We study the global statistics of molecular clouds formed by large scale colliding…

Astrophysics · Physics 2009-11-13 P. Hennebelle , R. Banerjee , E. Vazquez-Semadeni , R. Klessen , E. Audit

I model the multi-phase interstellar medium (ISM) randomly heated and shocked by supernovae, with gravity, differential rotation and other parameters we understand to be typical of the solar neighbourhood. The simulations are 3D extending…

Astrophysics of Galaxies · Physics 2017-12-15 Frederick Gent

H2 is the simplest and the most abundant molecule in the ISM, and its formation precedes the formation of other molecules. Understanding the dynamical influence of the environment and the interplay between the thermal processes related to…

Astrophysics of Galaxies · Physics 2016-02-24 Valeska Valdivia , Patrick Hennebelle , Maryvonne Gérin , Pierre Lesaffre

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

Thermal instability (TI) plays a crucial role in the formation of multiphase structures and their dynamics in the Interstellar Medium (ISM) and is a leading theory for cold cloud creation in various astrophysical environments. In this paper…

Astrophysics of Galaxies · Physics 2021-08-24 R. Michael Jennings , Yuan Li

We review recent results from numerical simulations and related models of MHD turbulence in the interstellar medium (ISM) and in molecular clouds. We discuss the implications of turbulence for the processes of cloud formation and evolution,…

Astrophysics · Physics 2007-05-23 E. Vazquez-Semadeni , E. C. Ostriker , T. Passot , C. F. Gammie , J. M. Stone

We provide a brief overview of recent advances and outstanding issues in simulations of interstellar turbulence, including isothermal models for interior structure of molecular clouds and larger-scale multiphase models designed to simulate…

Astrophysics of Galaxies · Physics 2011-05-05 Alexei G. Kritsuk , Sergey D. Ustyugov , Michael L. Norman

Calculations of equilibrium properties of dense matter predict that at subnuclear densities nuclei can be rodlike or slablike. To investigate whether transitions between phases with non-spherical nuclei can occur during the collapse of a…

We analyze the gravitational collapse of solids subject to gas drag in a protoplanetary disk. We also study the stirring of solids by turbulent fluctuations to determine the velocity dispersion and thickness of the midplane particle layer.…

Astrophysics · Physics 2007-05-23 Andrew N. Youdin

Gravitational instability is one of considerable mechanisms to explain the formation of giant planets. We study the gravitational stability for the protoplanetary disks around a protostar. The temperature and Toomre's Q-value are calculated…

Earth and Planetary Astrophysics · Physics 2019-03-18 Shigeo S. Kimura , Toru Tsuribe

Granular simulations are used to probe the particle scale dynamics at short, intermediate, and long time scales for gravity driven, dense granular flows down an inclined plane. On approach to the angle of repose, where motion ceases, the…

Soft Condensed Matter · Physics 2009-11-11 L. E. Silbert

Numerical simulations of pebble dynamics inside gas clumps formed by gravitational instability of protoplanetary discs are presented. We find that dust-mediated Rayleigh-Taylor instabilities transport pebbles inward rapidly via dense…

Earth and Planetary Astrophysics · Physics 2018-08-16 Sergei Nayakshin

The neutral interstellar medium (ISM) inside the Local Bubble (LB) has been known to have properties typical of the warm neutral medium (WNM). However, several recent neutral hydrogen (HI) absorption experiments show evidence for the…

Astrophysics · Physics 2009-06-23 Snezana Stanimirovic

The Interstellar Medium (ISM) is a complex, multi-phase system, where the history of the stars occurs. The processes of birth and death of stars are strongly coupled to the dynamics of the ISM. The observed chaotic and diffusive motions of…

Astrophysics of Galaxies · Physics 2011-02-02 D. Falceta-Goncalves

In this paper, by considering a simple fluid model, we investigate the role of phase transitions in the ISM on the galaxy scale gas dynamics. Cooling and heating timescales in the ISM are typically shorter than typical galactic rotation…

Astrophysics · Physics 2016-08-30 A. C. Quillen , C. B. Quillen

Supernova explosions, active galactic nuclei jets, galaxy--galaxy interactions and cluster mergers can drive turbulence in the circumgalactic medium (CGM) and in the intracluster medium (ICM). However, the exact nature of turbulence forced…

Astrophysics of Galaxies · Physics 2022-06-16 Rajsekhar Mohapatra , Christoph Federrath , Prateek Sharma