A grid of self-consistent MSG (MARCS-StaticWeather-GGchem) cool stellar, sub-stellar, and exoplanetary model atmospheres

Abstract

Computation of a grid of self consistent 1D model atmospheres of cool stars, sub-stellar objects and exoplanets in the effective temperature range 300K to 3000K, including cloud formation, chemical non-equilibrium effects, and stellar irradiation. The models are called MSG, because they are based on an iterative coupling between three well tested codes, the MARCS stellar atmosphere code, the StaticWeather cloud formation code and the GGchem chemical equilibrium code. It includes up-to-date molecular and atomic opacities, cloud formation and advanced chemical equilibrium calculations, and involves new numerical methods at low temperatures to allow robust convergence. The coupling between the MARCS radiative transfer and GGchem chemical equilibrium computations has made it possibly effectively to reach convergence based on electron pressure for the warmer models and gas pressure for the cooler models, enabling self-consistent modelling of stellar, sub-stellar and exoplanetary objects in a very wide range of effective temperatures. Here we describe the basic details of the models, with illustrative examples of cloudy and irradiated models as well as models based on non-equilibrium chemistry. The qualitative changes in the relative abundances of TiO, H2O, CH4, NH3, and other molecules in our models follow the observationally defined M, L, T (and Y) sequences, but reveal more complex and depth dependent abundance changes, and therefore a spectral classification depending on more parameters. The self consistent coupling to Static-Weather cloud computations, allows detailed comparison between nucleation and observed relative dimming of different spectral bands, with advanced applications for new identification methods of potential exoplanetary biology.

References in corpus (26)

• A grid of MARCS model atmospheres for late-type stars I. Methods and general properties
• CH in stellar atmospheres: an extensive linelist
• ExoMol molecular line lists XXXV: a rotation-vibration line list for hot ammonia
• The 2020 release of the ExoMol database: molecular line lists for exoplanet and other hot atmospheres
• A comparison of chemistry and dust cloud formation in ultracool dwarf model atmospheres
• ExoMol line lists XVIII. The high temperature spectrum of VO
• Methane, Carbon Monoxide, and Ammonia in Brown Dwarfs and Self-Luminous Giant Planets
• ExoMol line lists -- XXXIX. Ro-vibrational molecular line list for CO${}_2$
• ExoMol line lists VII: The rotation-vibration spectrum of phosphine up to 1500 K
• A hybrid line list for CH${}_4$ and hot methane continuum
• Consistent simulations of substellar atmospheres and non-equilibrium dust-cloud formation
• HELIOS-K 2.0 Opacity Calculator and Open-source Opacity Database for Exoplanetary Atmospheres
• Self-luminous and irradiated exoplanetary atmospheres explored with HELIOS
• ExoMol molecular line lists: IX The spectrum of AlO
• Exploring the substellar temperature regime down to ~550K
• ExoMol line lists VIII: A variationally computed line list for hot formaldehyde
• ExoMol molecular line lists - XXIII: spectra of PO and PS
• ExoMol line lists XXIV: A new hot line list for silicon monohydride, SiH
• Geometry of giant star model atmospheres: A consistency test
• ExoMol line lists XXXI: Spectroscopy of lowest eights electronic states of C${}_2$
• ExoMol molecular line lists X: The spectrum of sodium hydride
• Exomol molecular line lists VI: A high temperature line list for Phosphorus Nitride
• ExoMol line lists -- XLV. Rovibronic molecular line lists of calcium monohydride (CaH) and magnesium monohydride (MgH)
• No evidence for radius inflation in hot Jupiters from vertical advection of heat
• An Improved Near-Infrared Spectrum of the Archetype Y Dwarf WISEP J182831.08+265037.8
• Self-consistent atmosphere modeling with cloud formation for low-mass stars and exoplanets