相关论文: Water Clouds in Y Dwarfs and Exoplanets

The global circulation regime of the coolest brown dwarfs, the Y dwarfs, remains largely unexplored. We investigate the interplay between convection, rotation, and cloud thermal feedback using a selected sample of Y dwarf atmospheric…

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…

Cold, low-mass, field brown dwarfs are important for constraining the terminus of the stellar mass function, and also for optimizing atmospheric studies of exoplanets. In 2020 new model grids for such objects were made available:…

We present a new grid of cloudy atmosphere and evolution models for substellar objects. These models include the effect of refractory cloud species, including silicate clouds, on the spectra and evolution. We include effective temperatures…

A number of brown dwarfs are now known to be variable with observed amplitudes as large as 10-30% at some wavelengths. While spatial inhomogeneities in cloud coverage and thickness are likely responsible for much of the observed…

Orbital phase-dependent variations in thermal emission and reflected stellar energy spectra can provide meaningful constraints on the climate states of terrestrial extrasolar planets orbiting M dwarf stars. Spatial distributions of water…

The atmospheres of cool, helium-rich white dwarfs constitute an exotic and poorly explored physical regime of stellar atmospheres. Under physical conditions where the temperature varies from $\rm 1000K$ to $\rm 10000K$, the density can…

A model is proposed for the formation of water ice mantles on grains in interstellar clouds. This occurs by direct accretion of monomers from the gas, be they formed by gas or surface reactions. The model predicts the existence of a…

Constraining L dwarf properties from their spectra is challenging. Near-infrared spectra probe a limited range of pressures, while many species condense within their photospheres. Condensation creates two complexities: gas-phase species…

We present results from conducting a theoretical chemical analysis of a sample of benchmark companion brown dwarfs whose primary star is of type F, G or K. We summarize the entire known sample of these types of companion systems, termed…

Models of brown dwarf atmospheres suggest they exhibit complex physical behaviour. Observations have shown that they are indeed dynamic, displaying small photometric variations over timescales of hours. Here I report results of infrared…

Brown dwarfs are commonly regarded as easily-observed templates for exoplanet studies, with comparable masses, physical sizes and atmospheric properties. There is indeed considerable overlap in the photospheric temperatures of the coldest…

Substellar objects have extremely long life-spans. The cosmological consequence for older objects are low abundances of heavy elements, which results in a wide distribution of objects over metallicity, hence over age. Within their cool…

Observations suggest an abundance of water and paucity of methane in the majority of observed exoplanetary atmospheres. We isolate the effect of atmospheric processes to investigate possible causes. Previously, we studied the effect of…

The precipitation of cloud particles in brown dwarf and exoplanet atmospheres establishes an ongoing downward flux of condensable elements. To understand the efficiency of cloud formation, it is therefore crucial to quantify the…

We present a large forward-modeling analysis for 55 late-T (T7-T9) dwarfs, using low-resolution ($R\approx150$) near-infrared spectra and cloudless Sonora-Bobcat model atmospheres. We derive the objects' effective temperatures, surface…

We present a study of very low-mass stars and brown dwarfs in the rich star-forming core of the Rho Ophiuchi cloud complex. The selection of the sample relies on detecting the inherent water absorption characteristic in young substellar…

We examine the spectra and infrared colors of the cool methane-dominated atmospheres at Teff < 1400 K expected for young gas giant planets. We couple these spectral calculations to an updated version of the Marley et al. (2007) giant planet…

Brown dwarfs and giant gas extrasolar planets have cold atmospheres with a rich chemical compositions from which mineral cloud particles form. Their properties, like particle sizes and material composition, vary with height, and the mineral…

In this paper, we review the current theory of very low mass stars model atmospheres including the coolest known M~dwarfs, M~subdwarfs, and brown dwarfs, i.e. T$_{eff} \leq 5,000 $K and $-2.0 \le [M/H] \le +0.0$. We discuss ongoing efforts…