相关论文: Model Atmospheres From Very Low Mass Stars to Brow…

We obtained medium-resolution near-infrared spectra of seven young M9.5-L3 dwarfs classified in the optical. We aim to confirm the low surface gravity of the objects in the NIR. We also test whether atmospheric models correctly represent…

Understanding differences between sub-stellar spectral data and models has proven to be a major challenge, especially for self-consistent model grids that are necessary for a thorough investigation of brown dwarf atmospheres. Using the…

The large scale structure of a brown dwarf atmosphere is determined by an interplay of convection, radiation, dust formation, and gravitational settling, which possibly provides an explanation for the observed variability. The result is an…

State-of-the-art JWST observations are unveiling unprecedented views into the atmospheres of substellar objects in the infrared, further highlighting the importance of clouds. Current forward models struggle to fit the silicate clouds…

Observationally, spectra of brown dwarfs indicate the presence of dust in their atmospheres while theoretically it is not clear what prevents the dust from settling and disappearing from the regions of spectrum formation. Consequently,…

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…

We test state-of-the-art model atmospheres for young very low-mass stars and brown dwarfs in the infrared, by comparing the predicted synthetic photometry over 1.2-24 {\mu}m to the observed photometry of M-type spectral templates in…

The admitted, conventional scenario to explain the complex spectral evolution of brown dwarfs (BD) since their first detections twenty years ago, has always been the key role played by micron-size condensates, called "dust" or "clouds", in…

Dust formation in brown dwarf atmospheres is studied by utilising a model for driven turbulence in the mesoscopic scale regime. We apply a pseudo-spectral method where waves are created and superimposed within a limited wavenumber interval.…

We present new evolution sequences for very low mass stars, brown dwarfs and giant planets and use them to explore a variety of influences on the evolution of these objects. We compare our results with previous work and discuss the causes…

We present opacity sampling model atmospheres, synthetic spectra and colors for brown dwarfs and very low mass stars in two limiting case of dust grain formation: 1) inefficient gravitational settling i.e. the dust is distributed according…

We report an attempt to interpret the spectra of L and T dwarfs with the use of the Unified Cloudy Model (UCM). For this purpose, we extend the grid of the UCMs to the cases of log g = 4.5 and 5.5. The dust column density relative to the…

Clouds of metal-bearing condensates play a critical role in shaping the emergent spectral energy distributions of the coolest classes of low-mass stars and brown dwarfs, L and T dwarfs. Because condensate clouds in planetary atmospheres…

Growing observational evidence has suggested active meteorology in atmospheres of brown dwarfs (BDs) and directly imaged extrasolar giant planets (EGPs). In particular, a number of surveys have shown that near-IR brightness variability is…

We aim at understanding the formation of cloud layers in quasi-static substellar atmospheres. The time-dependent description presented in (Helling & Woitke 2006) is a kinetic model describing nucleation, growth and evaporation. It is…

Exoplanet and brown dwarf atmospheres commonly show signs of disequilibrium chemistry. In the James Webb Space Telescope era high resolution spectra of directly imaged exoplanets will allow the characterization of their atmospheres in more…

Very massive stars (VMS) dominate the light of young stellar populations and are sources of intense stellar feedback. Their evolution is mainly driven by strong wind mass loss, yet current evolution models make simplistic assumptions on…

We present a new suite of atmosphere models with flexible cloud parameters to investigate the effects of clouds on brown dwarfs across the L/T transition. We fit these models to a sample of 13 objects with well-known masses, distances, and…

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…

Brown dwarfs are massive, giant exoplanet analogues subject to variability and colour changes, known as the L/T transition, fundamental for their thermal evolution. The drivers of the L/T transition remain elusive, with atmospheric…