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[cea-02571500] A new set of atmosphere and evolution models for cool T–Y brown dwarfs and giant exoplanets  (5/15/20)   Moins
We present a new set of solar metallicity atmosphere and evolutionary models for very cool brown dwarfs and self-luminous giant exoplanets, which we term ATMO 2020. Atmosphere models are generated with our state-of-the-art 1D radiative-convective equilibrium code ATMO, and are used as surface boundary conditions to calculate the interior structure and evolution of 0.001–0.075 M⊙ objects. Our models include several key improvements to the input physics used in previous models available in the literature. Most notably, the use of a new H–He equation of state including ab initio quantum molecular dynamics calculations has raised the mass by ~1−2% at the stellar–substellar boundary and has altered the cooling tracks around the hydrogen and deuterium burning minimum masses. A second key improvement concerns updated molecular opacities in our atmosphere model ATMO, which now contains significantly more line transitions required to accurately capture the opacity in these hot atmospheres. This leads to warmer atmospheric temperature structures, further changing the cooling curves and predicted emission spectra of substellar objects. We present significant improvement for the treatment of the collisionally broadened potassium resonance doublet, and highlight the importance of these lines in shaping the red-optical and near-infrared spectrum of brown dwarfs. We generate three different grids of model simulations, one using equilibrium chemistry and two using non-equilibrium chemistry due to vertical mixing, all three computed self-consistently with the pressure-temperature structure of the atmosphere. We show the impact of vertical mixing on emission spectra and in colour-magnitude diagrams, highlighting how the 3.5−5.5 μm flux window can be used to calibrate vertical mixing in cool T–Y spectral type objects.

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Electronic structure Modélisation Fenhexamide EMISSION-SPECTRA Metadynamics Metamitron Approche mixte quantique/classique Molecular dynamics simulations DFT Chemical shift Au147 CONFIGURATION-INTERACTION Molecular data Dynamique Moléculaire Car-Parrinello Finite-temperature effects Ion trap Dynamique moléculaire Photoelectron spectra Argon DUST Piège à ions Carbonaceous grains PHOTODISSOCIATION REGIONS Dftb Density Functional Theory Infrared spectroscopy CONSTANTS Car-Parrinello molecular dynamics Modelling Photoionisation MINI-SYMPOSIUM SPECTROSCOPY OF INTERFACES Biodegradation Quantum chemistry LYING ELECTRONIC STATES PAH INFRARED-EMISSION Modeling Excited states Astrochemistry Molecular aggregates Line profiles / brown dwarfs Methods laboratory molecular Molecule-photon collisions Mass spectrometry Agrégats protonés MOLECULE Planets and satellites atmospheres GALAXIES Catalyse Barium Gold Interstellar extinction Chimie quantique Amorphous ISM molecules Matrice de gaz rare Effets de température Clusters Ne tagging spectroscopy Molecular dynamic simulation Agrégats moléculaires Profiles Atrazine DFTB Free energy surface Nanoparticles Molecular clusters CAH ISM lines and bands Auxiliary density functional theory Photon-dominated region PDR Argile Clay mineral Catalysis Brown dwarfs Pesticide POLARIZATION Molecular processes NMR Organochlorine pesticides Carbon cluster Molecular dynamics MAGNESIUM DEUTERIDE Optical spectra FAR-IR Fenhexamid IR EMISSION Nanoparticules Force fields Molecular modeling Energie renouvelable Niobates 22 pole cryogenic ion trap Alanine dipeptide Partial least squares EXTENDED RED EMISSION Champ de forces Métamitrone PAHS Infrared ISM