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We investigate the evolution of interfaces among phases of the interstellar medium with different temperature. It is found that, for some initial conditions, the dynamical effects related to conductive fronts are very important even if…

Astrophysics · Physics 2009-10-22 Andrea Ferrara , Yuri Shchekinov

Context. Multitransition CO observations of galaxy centers have revealed that significant fractions of the dense circumnuclear gas have high kinetic temperatures, which are hard to explain by pure photon excitation, but may be caused by…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-04 M. V. Kazandjian , R. Meijerink , I. Pelupessy , F. P. Israel , M. Spaans

The dependence of the cosmic ray intensity on Galactocentric distance is known to be much less rapid than that to be thought-to-be sources: supernova remnants. This is an old problem ('the radial gradient problem') which has led to a number…

Astrophysics of Galaxies · Physics 2015-12-23 Anatoly Erlykin , Arnold Wolfendale , Vladimir Dogiel

The large temperature difference between cold gas clouds around galaxies and the hot halos that they are moving through suggests that thermal conduction could play an important role in the circumgalactic medium. However, thermal conduction…

Astrophysics of Galaxies · Physics 2021-01-29 Richard Kooij , Asger Grønnow , Filippo Fraternali

It is shown that homogeneous line-broadening in a diffuse cold atom cloud is proportional to the resonant optical depth of the cloud. Further, it is demonstrated how the strong directionality of the coherent interactions causes the cloud's…

Atomic Physics · Physics 2016-09-21 R. T. Sutherland , Francis Robicheaux

Most massive galaxies host a supermassive black hole at their centre. Matter accretion creates an active galactic nucleus (AGN), forming a relativistic particle wind. The wind heats and pushes the interstellar medium, producing…

Astrophysics of Galaxies · Physics 2024-09-23 Martynas Laužikas , Kastytis Zubovas

In this paper we consider the effects of opacity regimes on the stability of self-gravitating protoplanetary discs to fragmentation into bound objects. Using a self-consistent 1-D viscous disc model, we show that the ratio of local cooling…

Astrophysics of Galaxies · Physics 2015-05-14 Peter Cossins , Giuseppe Lodato , Cathie Clarke

In an effort to model the observed energy spectrum of Cygnus X-1 as well as its hard X-ray lag by Comptonization in inhomogeneous clouds of hot electrons with spherical geometry and various radial density profiles we discovered that: 1)…

Astrophysics · Physics 2007-05-23 Xin-Min Hua , Demosthenes Kazanas , Wei Cui

We consider the collective scattering by a cloud of $N$ two-level atoms driven by an uniform radiation field. Dense atomic clouds can be described by a continuous density and the problem reduces to deriving the spectrum of the atom-atom…

Optics · Physics 2015-03-31 Romain Bachelard , Nicola Piovella , Philippe Courteille

We model the hydrodynamic interaction of a shock wave of an evolved supernova remnant with a small interstellar gas cloud like the ones observed in the Cygnus loop and in the Vela SNR. We investigate the interplay between radiative cooling…

Astrophysics · Physics 2009-11-11 S. Orlando , G. Peres , F. Reale , F. Bocchino , R. Rosner , T. Plewa , A. Siegel

Changes in aerosol concentrations can modify cloud brightness, producing a strong but poorly constrained influence on Earth's energy balance. Because cloud reflectivity depends on the size distribution of cloud droplets, and aerosol size…

Molecular clouds have broad linewidths suggesting turbulent supersonic motions in the clouds. These motions are usually invoked to explain why molecular clouds take much longer than a free-fall time to form stars. It has classically been…

Astrophysics · Physics 2011-02-11 Mordecai-Mark Mac Low

We perform time-dependent, 2DHD numerical simulations to study the dynamics of a slowly rotating accretion flow from sub-pc to pc scales under the irradiation from the central AGN. Compared to previous work, we improve the calculation of…

High Energy Astrophysical Phenomena · Physics 2015-06-15 Chao Liu , Feng Yuan , Jeremiah P. Ostriker , Zhaoming Gan , Xiaohong Yang

In dense molecular clouds collisions between dust grains alter the ISM-dust size distribution. We study this process by inserting the results from detailed numerical simulations of two colliding dust aggregates into a coagulation model that…

Solar and Stellar Astrophysics · Physics 2015-05-13 C. W. Ormel , D. Paszun , C. Dominik , A. G. G. M. Tielens

We provide a theoretical analysis of Radiative Shocks, defined as supercritical shocks accompanied by an ionization wave in front of the density jump. In particular, we look at the influence of opacity variation with temperature and photon…

Solar and Stellar Astrophysics · Physics 2011-05-10 M. Busquet , M. Klapisch , F. Thais

Clouds' efficiency at reflecting solar radiation and trapping the terrestrial one is strongly modulated by their diurnal cycle. Much attention has been paid to mean cloud properties due to their critical role in climate projections;…

Atmospheric and Oceanic Physics · Physics 2018-03-06 Jun Yin , Amilcare Porporato

The effects of the UV background radiation on the formation of sub-galactic clouds are studied by means of one-dimensional hydrodynamical simulations. The radiative transfer of the ionizing photons due to the absorption by HI, HeI and HeII,…

Astrophysics · Physics 2009-10-31 Tetsu Kitayama , Satoru Ikeuchi

With Planck and Herschel, we now have the spectral coverage and angular resolution required to observe dense and cold molecular clouds. As these clouds are optically thick at short wavelength but optically thin at long wavelength, it is…

Atmospheric variations over time and space boost planetary cooling, as outgoing internal flux responds to stellar radiation and opacity. Vertical mixing regulates this cooling. Our study examines how gravity waves or large-scale induced…

Earth and Planetary Astrophysics · Physics 2026-01-05 Wei Zhong , Zhen-Tai Zhang , Bo Ma , Xianyu Tan , Dong-dong Ni , Cong Yu

Coalescence may not occur immediately when droplets impact a liquid film. Despite the prevalence of the high-temperature condition during the impact process in many applications, the effect of droplet temperature on droplet coalescence is…

Fluid Dynamics · Physics 2025-04-24 Zhigang Xu , Haicheng Qi , Tianyou Wang , Zhizhao Che
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