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We derive an analytic prediction for the star formation rate in environments ranging from normal galactic disks to starbursts and ULIRGs in terms of the observables of those systems. Our calculation is based on three premises: (1) star…

Astrophysics · Physics 2010-04-06 Mark R. Krumholz , Christopher F. McKee

We consider the dynamical evolution of an interstellar cloud that is initially in thermal equilibrium in the warm phase and is then subjected to a sudden increase in the pressure of its surroundings. We find that if the initial plasma beta…

Astrophysics · Physics 2009-11-13 A. J. Lim , S. A. E. G. Falle , T. W. Hartquist

This paper describes 3D simulations of the formation of collapsing cold clumps via thermal instability inside a larger cloud complex. The initial condition was a diffuse atomic, stationary, thermally unstable, 200pc diameter spherical cloud…

Astrophysics of Galaxies · Physics 2019-03-20 C. J. Wareing , S. A. E. G. Falle , J. M. Pittard

Cool, dense material is frequently observed to permeate the hot, tenuous solar corona in the form of prominences, spicules and coronal rain. Both the cool material and surrounding corona exist at temperatures that are effectively thermally…

Solar and Stellar Astrophysics · Physics 2026-01-30 B. Snow , A. Hillier

Sheet-like clouds are common in turbulent gas and perhaps form via collisions between turbulent gas flows. Having examined the evolution of an isothermal shocked slab in an earlier contribution, in this work we follow the evolution of a…

Astrophysics of Galaxies · Physics 2015-06-23 S. Anathpindika

This letter presents a numerical study of the evolution of an emission line cloud of initial density 10 cm$^{-3}$, temperature $10^4$ K, and size 200 pc, being overtaken by a strong shock wave. Whereas previous simple models proposed that…

Astrophysics · Physics 2009-11-07 Garrelt Mellema , Jaron Kurk , Huub Rottgering

Recent numerical simulations of the interstellar medium driven by energy input from supernovae and stellar winds indicate that HI clouds can be formed by compression in shock waves and colliding turbulent streams without any help from…

Astrophysics · Physics 2007-05-23 Anvar Shukurov

A critical component of particle acceleration in astrophysical shocks is the non-resonant (Bell) instability, where the streaming of cosmic rays (CRs) leads to the amplification of magnetic fields necessary to scatter particles. In this…

High Energy Astrophysical Phenomena · Physics 2025-02-11 Emily Lichko , Damiano Caprioli , Benedikt Schroer , Siddhartha Gupta

The recent observations of rippled structures on the surface of the Orion molecular cloud (Bern\'{e} et al. 2010), have been attributed to the Kelvin-Helmholtz (KH) instability. The wavelike structures which have mainly seen near…

Astrophysics of Galaxies · Physics 2017-07-26 Akram Yaghouti , Mohsen Nejad-Asghar , Shahram Abbassi

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

The observed star formation and wind outflow rates in galaxies suggest cold gas must be continually replenished via infalling clouds or streams. Previous studies have highlighted the importance of cooling-induced condensation on such gas,…

Astrophysics of Galaxies · Physics 2025-02-26 Ish Kaul , Brent Tan , S. Peng Oh , Nir Mandelker

The linear analysis of the instability due to vertical shear in the dust layer of the solar nebula is performed. The following assumptions are adopted throughout this paper: (1) The self-gravity of the dust layer is neglected. (2) One fluid…

Astrophysics · Physics 2009-11-07 Naoki Ishitsu , Minoru Sekiya

To understand the formation of a magnetically dominated molecular cloud out of an atomic cloud, we follow the dynamical evolution of the cloud with a time-dependent axisymmetric magnetohydrodynamic code. A thermally stable warm atomic cloud…

Astrophysics · Physics 2009-11-13 S. Van Loo , S. A. E. G. Falle , T. W. Hartquist , T. J. T. Moore

Star formation in high-redshift dwarf galaxies is a key to understand early galaxy evolution in the early Universe. Using the three-dimensional hydrodynamics code GIZMO, we study the formation mechanism of cold, high-density gas clouds in…

Astrophysics of Galaxies · Physics 2018-01-31 Shohei Arata , Hidenobu Yajima , Kentaro Nagamine

We test the hypothesis that the starless cores may be gravitationally bound clouds supported largely by thermal pressure by comparing observed molecular line spectra to theoretical spectra produced by a simulation that includes…

Astrophysics · Physics 2009-11-13 Eric Keto , George Field

The Goldreich and Ward (1973) (axisymmetric) gravitational instability of a razor thin particle layer occurs when the Toomre parameter $Q_T \equiv c_p \Omega_0 / \pi G \Sigma_p < 1$ ($c_p$ being the particle dispersion velocity).…

Earth and Planetary Astrophysics · Physics 2015-04-03 Karim Shariff , Jeffrey N. Cuzzi

We consider the impact of thermal conduction in clusters of galaxies on the (unmagnetized) interface between a cold gaseous cloud and a hotter gas flowing over the cloud (the so-called cold front). We argue that near the stagnation point of…

Astrophysics · Physics 2008-11-26 F. Xiang , E. Churazov , K. Dolag , V. Springel , A. Vikhlinin

Shear flows, ubiquitous in space and astrophysical plasmas, can accelerate particles through turbulence excited by the Kelvin-Helmholtz instability. We present the first numerical study of particle acceleration in non-relativistic,…

High Energy Astrophysical Phenomena · Physics 2025-12-16 Mingxuan Liu , Mateusz Ruszkowski , Ellen Zweibel , Xiaochen Sun , Damiano Caprioli , Naixin Liang , Siang Peng Oh , Anatoly Spitkovsky

High-energy gamma ray emission has been detected recently from supernovae remnants (SNRs) and their surroundings. The existence of molecular clouds near some of the SNRs suggests that the gamma rays originate predominantly from p-p…

High Energy Astrophysical Phenomena · Physics 2015-06-03 Huirong Yan , A. Lazarian , R. Schlickeiser

Thermal instability (TI) is a trigger mechanism, which can explain the formation of small condensations through some regions of the interstellar clouds. The instability criterion for flat geometry approximations has been investigated in…

Astrophysics of Galaxies · Physics 2024-12-24 Mohsen Nejad-Asghar