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Dust and gas energetics are incorporated into a cluster-scale simulation of star formation in order to study the effect of heating and cooling on the star formation process. We build on our previous work by calculating separately the dust…

Solar and Stellar Astrophysics · Physics 2015-06-05 Hugo Martel , Andrea Urban , Neal J. Evans

We study a one-dimensional fluid of hard-rods interacting each other via binary inelastic collisions and a short ranged square-well potential. Upon tuning the depth and the sign of the well, we investigate the interplay between dissipation…

Statistical Mechanics · Physics 2009-11-11 Umberto Marini-Bettolo-Marconi , Maurizio Natali , Giulio Costantini , Fabio Cecconi

We report a combined experimental and theoretical study of collision-induced dipolar relaxation in a cold spin-polarized gas of atomic nitrogen (N). We use buffer gas cooling to create trapped samples of 14N and 15N atoms with densities…

Atomic Physics · Physics 2011-03-07 T. V. Tscherbul , J. Klos , A. Dalgarno , B. Zygelman , Z. Pavlovic , M. T. Hummon , H-I Lu , E. Tsikata , J. M. Doyle

I explore the thermal evolution and ionization states in gas cooling from an initially hot state in the presence of external photoionizing radiation. I compute the equilibrium and nonequilibrium cooling efficiencies, heating rates, and ion…

Astrophysics of Galaxies · Physics 2017-07-05 Orly Gnat

We study the influence of the choice of cooling function on the formation of molecular clouds in high-resolution three-dimensional simulations of converging flows. We directly compare the results obtained using the simple, parametrized…

Astrophysics of Galaxies · Physics 2015-06-15 Milica Micic , Simon C. O. Glover , Robi Banerjee , Ralf S. Klessen

The collapse of the primordial gas in the density regime $\sim 10^{8}\hbox{--}10^{10}$ cm$^{-3}$ is controlled by the three-body $\rm H_2$ formation process, in which the gas can cool faster than free-fall time $\hbox{--}$ a condition…

Astrophysics of Galaxies · Physics 2015-10-30 Jayanta Dutta

Radiative cooling is an important ingredient in hydrodynamical models involving evolution of high temperature plasmas. Unfortunately, calculating an accurate cooling coefficient generally requires the solution of over a hundred differential…

Astrophysics · Physics 2009-11-06 Robert A. Benjamin , Bradford A. Benson , Donald P. Cox

Our knowledge about the "cold" Universe often relies on molecular spectra. A general property of such spectra is that the energy level populations are rarely at local thermodynamic equilibrium. Solving the radiative transfer thus requires…

Instrumentation and Methods for Astrophysics · Physics 2018-01-23 Jérôme Loreau , François Lique , Alexandre Faure

Cooling of primordial gas plays a crucial role in the birth of the first structures in our Universe. Due to the low fractional abundance of molecular species at high redshifts, spontaneous emission rather than collisions represents the most…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-27 Carla Maria Coppola , Lorenzo Lodi , Jonathan Tennyson

Using a quantum-mechanical close-coupling method, we calculate cross sections for fine structure excitation and relaxation of Si and S atoms in collisions with atomic hydrogen. Rate coefficients are calculated over a range of temperatures…

Atomic Physics · Physics 2024-12-10 Pei-Gen Yan , James F. Babb

In a granular gas, inelastic collisions produce an instability in which the constituent particles cluster heterogeneously. These clusters then interact with each other, further decreasing their kinetic energy. We report experiments of the…

Soft Condensed Matter · Physics 2015-06-17 Justin C. Burton , Peter Y. Lu , Sidney R. Nagel

Cooling and heating functions describe how radiative processes impact the thermal state of a gas as a function of its temperature and other physical properties. In a most general case the functions depend on the detailed distributions of…

Astrophysics of Galaxies · Physics 2022-09-05 David Robinson , Camille Avestruz , Nickolay Y. Gnedin

We study a Bose-condensed gas at finite temperature, in which the particles of the condensate and of the thermal cloud are constrained to move in a plane under radial harmonic confinement and interact via strictly two-dimensional…

Soft Condensed Matter · Physics 2009-11-10 K. K. Rajagopal , P. Vignolo , M. P. Tosi

The free cooling process in the inelastic hard sphere system is studied by analysing the data from large scale molecular dynamics simulations on a three dimensional system. The initial energy decay, the velocity distribution function, and…

Statistical Mechanics · Physics 2009-11-10 Ryo Kawahara , Hiizu Nakanishi

The conductivity of extremely high mobility dilute two-dimensional holes in GaAs changes linearly with temperature in the insulating side of the metal-insulator transition. Hopping conduction, characterized by an exponentially decreasing…

Mesoscale and Nanoscale Physics · Physics 2009-11-10 Hwayong Noh , M. P. Lilly , D. C. Tsui , J. A. Simmons , L. N. Pfeiffer , K. W West

We present numerical computations and analysis of atomic to molecular (HI-to-H$_2$) transitions in cool ($\sim$100 K) low-metallicity dust-free (primordial) gas, in which molecule formation occurs via cosmic-ray driven negative ion…

Astrophysics of Galaxies · Physics 2021-10-27 Amiel Sternberg , Alon Gurman , Shmuel Bialy

We present a study of the temperature and density dependence of the resistivity of an extremely high quality two-dimensional hole system grown on the (100) surface of GaAs. For high densities in the metallic regime ($p\agt 4 \times 10^{9}$…

Mesoscale and Nanoscale Physics · Physics 2009-11-13 M. J. Manfra , E. H. Hwang , S. Das Sarma , L. N. Pfeiffer , K. W. West , A. M. Sergent

We study the temperature dependence of the conductivity of the 2D electronic solid. In realistic samples, a domain structure forms in the solid and each domain randomly orients in the absence of the in-plane field. At higher temperature,…

Mesoscale and Nanoscale Physics · Physics 2009-11-10 Shi-Jie Yang , Yue Yu

H2 formation is an important process in post-shock regions, since H2 is an active participant in the cooling and shielding of the environment. The onset of H2 formation therefore has a strong effect on the temperature and chemical evolution…

Solar and Stellar Astrophysics · Physics 2015-05-18 H. M. Cuppen , L. E. Kristensen , E. Gavardi

The impact of the dispersion of the transport coefficients on the structure of the energy distribution function for charge carriers far from equilibrium has been investigated in effective-medium approximation for model densities of states.…

Disordered Systems and Neural Networks · Physics 2009-11-10 O. Bleibaum , H. Boettger , V. V. Bryksin