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Many stars, active galactic nuclei, accretion discs etc. are affected by the stochastic variations of temperature, turbulent gas motions, magnetic fields, number densities of atoms and dust grains. These stochastic variations influence on…

Solar and Stellar Astrophysics · Physics 2017-12-20 N. A. Silant'ev , G. A. Alekseeva , V. V. Novikov

Numerous observational evidence has suggested the presence of active meteorology in the atmospheres of brown dwarfs. A near-infrared brightness variability has been observed. Clouds have a major role in shaping the thermal structure and…

Earth and Planetary Astrophysics · Physics 2022-05-04 Maxence Lefèvre , Xianyu Tan , Elspeth K. H. Lee , R. T. Pierrehumbert

In dense parts of interstellar clouds (> 10^5 cm^-3), dust & gas are expected to be in thermal equilibrium, being coupled via collisions. However, previous studies have shown that the temperatures of the dust & gas may remain decoupled even…

Solar and Stellar Astrophysics · Physics 2015-08-05 E. Koumpia , P. M. Harvey , V. Ossenkopf , F. F. S. van der Tak , B. Mookerjea , A. Fuente , C. Kramer

Observations of protoplanetary disks (PPDs) at sub-mm wavelengths suggest that polarisation is caused by scattering of thermal radiation. Most of the dust models that are used to explain these observations have major drawbacks: They either…

Solar and Stellar Astrophysics · Physics 2021-04-21 Robert Brunngräber , Sebastian Wolf

Recent observations of brown dwarf spectroscopic variability in the infrared infer the presence of patchy cloud cover. This paper proposes a mechanism for producing inhomogeneous cloud coverage due to the depletion of cloud particles…

Solar and Stellar Astrophysics · Physics 2015-05-19 Craig R. Stark , Christiane Helling , Declan A. Diver

Radiation transport plays important roles in stellar atmospheres, but the effects of turbulence are being obscured by other effects such as stratification. Using radiative hydrodynamic simulations of forced turbulence, we determine the…

Fluid Dynamics · Physics 2021-09-29 Axel Brandenburg , Upasana Das

Multi-wavelength observations in the sub-mm regime provide information on the distribution of both the dust column density and the effective dust temperature in molecular clouds. In this study, we created high-resolution and…

Astrophysics of Galaxies · Physics 2018-11-28 Birgit Hasenberger , Marco Lombardi , João Alves , Jan Forbrich , Alvaro Hacar , Charles J. Lada

We use the RASS-SDSS galaxy cluster sample to compare the quality of optical and X-ray luminosities as predictors of other cluster properties such as their masses, temperatures, and velocity dispersions. We use the SDSS spectroscopic data…

Astrophysics · Physics 2010-11-04 P. Popesso , A. Biviano , H. Bhoeringer , M. Romaniello , W. Voges

The importance of inter-particle radiation for clusters of gray and diffuse particles is investigated. The radiative cooling of each individual particle is found to vary strongly with its position in the cluster, and a mean radiative…

Optics · Physics 2014-04-29 Nils Erland L. Haugen , Reginald E. Mitchell

A major challenge in CGM studies is determining the three-dimensional (3D) properties from the observed projected observations. Here, we decompose the 3D gas density and spatial distribution of cool clouds by fitting a cool CGM model with…

Astrophysics of Galaxies · Physics 2025-03-04 Hang Yang , Zhijie Qu , Joel N. Bregman , Li Ji

Large-scale dust heating and cooling in the diffuse medium of M31 is studied using the HiRes IRAS maps in conjunction with UV, optical (UBV) and the HI maps. A dust heating/cooling model is developed based on a radiative transfer model…

Astrophysics · Physics 2009-10-28 Cong Xu , George Helou

The project Galactic Cold Cores has made Herschel observations of interstellar clouds where the Planck satellite survey has located cold and compact clumps. The sources range from starless clumps to protostellar cores. We examine 116…

The thermal emission of dust is one of the most important tracers of the interstellar medium: multi-wavelength photometry in the far-infrared (FIR) and submillimeter (submm) can be fitted with a model, providing estimates of the dust mass.…

Astrophysics of Galaxies · Physics 2020-10-07 Lapo Fanciullo , Francisca Kemper , Peter Scicluna , Thavisha E. Dharmawardena , Sundar Srinivasan

Hot Jupiters, due to the proximity to their parent stars, are subjected to a strong irradiating flux which governs their radiative and dynamical properties. We compute a suite of 3D circulation models with dual-band radiative transfer,…

Earth and Planetary Astrophysics · Physics 2015-06-03 Rosalba Perna , Kevin Heng , Frederic Pont

The hot star wind momentum problem \eta = mdot*vinfty/(L/c) >> 1 is revisited, and it is shown that the conventional belief, that it can be solved by a combination of clumping of the wind and multiple scattering of photons, is not…

Astrophysics · Physics 2009-11-10 J C Brown , J P Cassinelli , Q Li , A F Kholtygin , R Ignace

Atoms and molecules, and in particular CO, are important coolants during the evolution of interstellar star-forming gas clouds. The presence of dust grains, which allow many chemical reactions to occur on their surfaces, strongly impacts…

Solar and Stellar Astrophysics · Physics 2015-06-17 S. Hocuk , S. Cazaux , M. Spaans

With dayside temperatures hot enough to sustain a magma ocean and a silicate atmosphere, lava planets are the best targets to study the atmosphere of a rocky world. In the absence of nightside heating, the entire atmosphere collapses near…

Earth and Planetary Astrophysics · Physics 2024-12-02 T. Giang Nguyen , Nicolas B. Cowan , Lisa Dang

We find that clouds of optically-thin, pressure-confined gas are prone to fragmentation as they cool below $\sim10^6$ K. This fragmentation follows the lengthscale $\sim{c}_{\text{s}}\,t_{\text{cool}}$, ultimately reaching very small scales…

Astrophysics of Galaxies · Physics 2018-05-10 Michael McCourt , S. Peng Oh , Ryan M. O'Leary , Ann-Marie Madigan

When comparing nebular electron densities derived from collisionally excited lines (CELs) to those estimated using the emission measure, significant discrepancies are common. The standard solution is to view nebulae as aggregates of dense…

Astrophysics of Galaxies · Physics 2019-12-20 Brandon M. Bergerud , Steven R. Spangler , Kara M. Beauchamp

Spectropolarimetry from the near IR to the far UV of light scattered by dust provides a valuable diagnostic of the dust composition, grain size distribution and spatial distribution. To facilitate the use of this diagnostic, we present…

Astrophysics · Physics 2009-10-31 Victor G. Zubko , Ari Laor