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Brown dwarfs and giant gas planets are substellar objects whose spectral appearance is determined by the chemical composition of the gas and the solids/liquids in the atmosphere. Atmospheres of substellar objects possess two major scale…

天体物理学 · 物理学 2007-05-23 Christiane Helling

Over the last decade {\it ab initio} modeling of material properties has become widespread in diverse fields of research. It has proved to be a powerful tool for predicting various properties of matter under extreme conditions. We apply…

太阳与恒星天体物理 · 物理学 2015-05-20 Piotr M. Kowalski , Mukremin Kilic

The color-magnitude (CM) diagram of cool dwarfs and brown dwarfs based on the recent astrometry data is compared with the CM diagram transformed from the theoretical evolutionary tracks via the unified cloudy models (UCMs) of L and T…

天体物理学 · 物理学 2009-11-07 Takashi Tsuji , Tadashi Nakajima

Recent years have seen excellent progress in modeling the entrainment of T $\sim$ $10^4$K atomic gas in galactic winds. However, the entrainment of cool, dusty T $\sim$ 10-100K molecular gas, which is also observed outflowing at high…

星系天体物理 · 物理学 2024-04-24 Zirui Chen , S. Peng Oh

Using a general circulation model (GCM), we investigate trends in simulated hot Jupiter atmospheres for a range of irradiation temperatures (1,500 - 4,000 K), surface gravities (10 and 40 m s-2), and cloud conditions. Our models include…

地球与行星天体物理 · 物理学 2021-02-24 Michael T. Roman , Eliza M. -R. Kempton , Emily Rauscher , Caleb K. Harada , Jacob L. Bean , Kevin B. Stevenson

We have calculated the radiation field, dust grain temperatures, and far infrared emissivity of numerical models of turbulent molecular clouds. When compared to a uniform cloud of the same mean optical depth, most of the volume inside the…

天体物理学 · 物理学 2009-11-10 Thomas Bethell , Ellen Zweibel , Fabian Heitsch , J. S. Mathis

Clouds form in atmospheres of brown dwarfs and planets. The cloud particle formation processes are similar to the dust formation process studied in circumstellar shells of AGB stars and in Supernovae. Cloud formation modelling in substellar…

太阳与恒星天体物理 · 物理学 2021-06-04 E. K. H. Lee , Ch. Helling , H. Giles , S. T. Bromley

Reliable modeling of the atmospheres of cool white dwarfs is crucial for understanding the atmospheric evolution of these stars and for accurate white dwarfs cosmochronology. Over the last decade {\it ab initio} modeling entered many…

太阳与恒星天体物理 · 物理学 2015-05-20 Piotr M. Kowalski

The James Webb Space Telescope (JWST) offers exceptional spectral resolution and wavelength coverage, which are essential for studying the coldest brown dwarfs, particularly Y dwarfs. These objects are at the cold end of the sub-stellar…

太阳与恒星天体物理 · 物理学 2026-01-21 A. Lueber , D. Kitzmann , K. Heng

Ultra-cool brown dwarfs offer a unique window into understanding substellar atmospheric physics and chemistry. Their strong molecular absorption bands at infrared wavelengths, Jupiter-like radii, cool temperatures, and lack of complicating…

太阳与恒星天体物理 · 物理学 2019-05-29 Joseph A. Zalesky , Michael R. Line , Adam C. Schneider , Jennifer Patience

We present a new generation of substellar atmosphere and evolution models, appropriate for application to studies of L, T, and Y-type brown dwarfs and self-luminous extrasolar planets. The atmosphere models describe the expected…

We present evolutionary calculations for very-low-mass stars and brown dwarfs based on synthetic spectra and non-grey atmosphere models which include dust formation and opacity, i.e. objects with $\te\simle 2800$ K. The interior of the most…

天体物理学 · 物理学 2008-11-26 G. Chabrier , I. Baraffe , F. Allard , P. Hauschildt

One of the mechanisms suggested for the L to T dwarf spectral type transition is the appearance of relatively cloud-free regions across the disk of brown dwarfs as they cool. The existence of partly cloudy regions has been supported by…

太阳与恒星天体物理 · 物理学 2015-05-20 Mark S. Marley , Didier Saumon , Colin Goldblatt

The temperature of interstellar dust particles is of great importance to astronomers. It plays a crucial role in the thermodynamics of interstellar clouds, because of the gas-dust collisional coupling. It is also a key parameter in…

星系天体物理 · 物理学 2017-08-09 S. Hocuk , L. Szucs , P. Caselli , S. Cazaux , M. Spaans , G. B. Esplugues

We have calculated a grid of more than 700 model atmospheres valid for a wide range of parameters encompassing the coolest known M~dwarfs, M~subdwarfs and brown dwarf candidates: $1500\le \teff \le 4000\,$K, $3.5\le \log(g)\le 5.5$, and…

天体物理学 · 物理学 2009-10-28 France Allard , Peter H. Hauschildt

We test emission models of circum-nuclear dust torii around quasars, at low and high redshifts, by using a large collection of photometric data for an unbiased sample of 120 optically-selected objects with millimetric and sub-millimetric…

天体物理学 · 物理学 2009-10-31 Paola Andreani , Alberto Franceschini , Gianluigi Granato

We fit archival near-infrared spectra of 305 brown dwarfs with atmosphere models from the Sonora and Phoenix groups. Using the parameters of the best-fit models as estimates for the physical properties of the brown dwarfs in our sample, we…

太阳与恒星天体物理 · 物理学 2025-05-05 Savanah K. Turner , Denise C. Stephens , Conner B. Scoresby , Josh A. Miller

Dust clouds influence the atmospheric structure of brown dwarfs, and they affect the heat transfer and change the gas-phase chemistry. However, the physics of their formation and evolution is not well understood. In this letter, we predict…

天体物理学 · 物理学 2016-08-30 CH. Helling , W. -F. Thi , P. Woitke , M. Fridlund

As a result of competing physical mechanisms, the atmospheric composition of white dwarfs changes throughout their evolution, a process known as spectral evolution. Because of the ambiguity of their atmospheric compositions and the…

太阳与恒星天体物理 · 物理学 2019-06-19 Simon Blouin , Patrick Dufour , Christian Thibeault , Nicole F. Allard

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…

地球与行星天体物理 · 物理学 2024-12-02 T. Giang Nguyen , Nicolas B. Cowan , Lisa Dang