The spectrum of hot methane in astronomical objects using a comprehensive computed line list

Abstract

Hot methane spectra are important in environments ranging from flames to the atmospheres of cool stars and exoplanets. A new spectroscopic line list, 10to10, for ${}^{12}$CH${}_4$ containing almost 10 billion transitions is presented. This comprehensive line list covers a broad spectroscopic range and is applicable for temperatures up to 1 500 K. Previous methane data are incomplete leading to underestimated opacities at short wavelengths and elevated temperatures. Use of 10to10 in models of the bright T4.5 brown dwarf 2MASS 0559-14 leads to significantly better agreement with observations and in studies of the hot Jupiter exoplanet HD 189733b leads to up to a twentifold increase in methane abundance. It is demonstrated that proper inclusion of the huge increase in hot transitions which are important at elevated temperatures is crucial for accurate characterizations of atmospheres of brown dwarfs and exoplanets, especially when observed in the near-infrared.

arXiv commentPNAS, Early Edition, June 16, 2014

References in corpus (41)

• A map of the day-night contrast of the extrasolar planet HD 189733b
• The Infrared Telescope Facility (IRTF) Spectral Library: Cool Stars
• A high accuracy computed water line list
• An Infrared Spectroscopic Sequence of M, L and T Dwarfs
• Chemical Equilibrium Abundances in Brown Dwarf and Extrasolar Giant Planet Atmospheres
• ELODIE metallicity-biased search for transiting Hot Jupiters II. A very hot Jupiter transiting the bright K star HD189733
• Line and Mean Opacities for Ultracool Dwarfs and Extrasolar Planets
• A Neptune-Mass Planet Orbiting the Nearby M Dwarf GJ 436
• A Unified Near Infrared Spectral Classification Scheme for T Dwarfs
• ExoMol: molecular line lists for exoplanet and other atmospheres
• The prevalence of dust on the exoplanet HD 189733b from Hubble and Spitzer observations
• Hubble Space Telescope Transmission Spectroscopy of the Exoplanet HD 189733b: High-altitude atmospheric haze in the optical and near-UV with STIS
• ExoMol line lists IV: The rotation-vibration spectrum of methane up to 1500 K
• The Discovery of Y Dwarfs Using Data from the Wide-field Infrared Survey Explorer (WISE)
• L and T Dwarf Models and the L to T Transition
• The 0.8-14.5 micron Spectra of Mid-L to Mid-T Dwarfs: Diagnostics of Effective Temperature, Grain Sedimentation, Gas Transport, and Surface Gravity
• A featureless transmission spectrum for the Neptune-mass exoplanet GJ 436b
• The climate of HD 189733b from fourteen transits and eclipses measured by Spitzer
• Atomic and Molecular Opacities for Brown Dwarf and Giant Planet Atmospheres
• High C/O Ratio and Weak Thermal Inversion in the Very Hot Atmosphere of Exoplanet WASP-12b
• Possible thermochemical disequilibrium in the atmosphere of the exoplanet GJ 436b
• A Gaussian process framework for modelling instrumental systematics: application to transmission spectroscopy
• Compositional diversity in the atmospheres of hot Neptunes, with application to GJ 436b
• Multi-Wavelength Constraints on the Day-Night Circulation Patterns of HD 189733b
• A ground-based near-infrared emission spectrum of the exoplanet HD 189733b
• Search for Carbon Monoxide in the atmosphere of the Transiting Exoplanet HD189733b
• Transit spectrophotometry of the exoplanet HD189733b. I. Searching for water but finding haze with HST NICMOS
• Probing the haze in the atmosphere of HD 189733b with HST/WFC3 transmission spectroscopy
• A Spitzer Transmission Spectrum for the Exoplanet GJ 436b, Evidence for Stellar Variability, and Constraints on Dayside Flux Variations
• K-H_2 Quasi-molecular absorption detected in the T-dwarf epsilon Indi Ba
• Vibrational transition moments of CH${}_4$ from first principles
• Methane in the atmosphere of the transiting hot Neptune GJ436b?
• The Near-infrared Spectrum of the Brown Dwarf Gliese 229B
• Infrared Transmission Spectra for Extrasolar Giant Planets
• Near-Infrared Multi-Band Photometry of the Substellar Companion GJ 758 B
• The atmospheric chemistry of the warm Neptune GJ 3470b: influence of metallicity and temperature on the CH4/CO ratio
• Modelling the Spectra of Planets, Brown Dwarfs and Stars using VSTAR
• Transit spectrophotometry of the exoplanet HD189733b. II. New Spitzer observations at 3.6 microns
• Physical parameters of T dwarfs derived from high-resolution near-infrared spectra
• The Near-IR Spectrum of Titan Modeled with an Improved Methane Line List
• TAU: A 1D radiative transfer code for transmission spectroscopy of extrasolar planet atmospheres

Cited by in corpus (48)

• The ExoMol database: molecular line lists for exoplanet and other hot atmospheres
• 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
• ExoCross: a general program for generating spectra from molecular line lists
• ExoMol line lists VII: The rotation-vibration spectrum of phosphine up to 1500 K
• Uniform Atmospheric Retrieval Analysis of Ultracool Dwarfs I: Characterizing Benchmarks, Gl570D and HD3651B
• A hybrid line list for CH${}_4$ and hot methane continuum
• The ExoMolOP Database: Cross-sections and k-tables for Molecules of Interest in High-Temperature Exoplanet Atmospheres
• ExoMol molecular line lists -- XXXVII: spectra of acetylene
• Atmospheric Regimes and Trends on Exoplanets and Brown Dwarfs
• ExoMol molecular line lists - XXVII: spectra of C2H4
• Exoplanet atmospheres with GIANO II. Detection of molecular absorption in the dayside spectrum of HD 102195b
• Strong biases in retrieved atmospheric composition caused by strong day-night chemical heterogeneities
• Perspective: Accurate ro-vibrational calculations on small molecules
• Symmetry adapted ro-vibrational basis functions for variational nuclear motion calculations: TROVE approach
• The ExoMol project: Software for computing large molecular line lists
• ExoMol Line List XXI: Nitric Oxide (NO)
• The ExoMol Atlas of Molecular Opacities
• The LEECH Exoplanet Imaging Survey: Characterization of the Coldest Directly Imaged Exoplanet, GJ 504 b, and Evidence for Super-Stellar Metallicity
• Pre-Born-Oppenheimer Molecular Structure Theory
• Empirical line lists and absorption cross sections for methane at high temperature
• Radiative lifetimes and cooling functions for astrophysically important molecules
• Methane and Ammonia in the near-infrared spectra of late T dwarfs
• Laboratory spectra of hot molecules: data needs for hot super-Earth exoplanets
• The Dawes Review 3: The Atmospheres of Extrasolar Planets and Brown Dwarfs
• A highly accurate {\it ab initio} potential energy surface for methane
• ExoMol line lists -- XXII. The rotation-vibration spectrum of silane up to 1200 K
• Sub-Doppler Double-Resonance Spectroscopy of Methane Using a Frequency Comb Probe
• A global potential energy surface and dipole moment surface for silane
• Towards multi-dimensional analysis of transmission spectroscopy. Part II: Day-night induced biases in retrievals from hot to ultra-hot Jupiters
• ExoMol molecular line lists: XI The spectrum of nitric acid
• The EChO science case
• Polarized Radiative Transfer in Planetary Atmospheres and the Polarization of Exoplanets
• ExoMol line lists -- XLV. Rovibronic molecular line lists of calcium monohydride (CaH) and magnesium monohydride (MgH)
• Data availability and requirements relevant for the Ariel space mission and other exoplanet atmosphere applications
• WASP-117 b: an eccentric hot-Saturn as a future complex chemistry laboratory
• ExoMol line lists - XXIX. The rotation-vibration spectrum of methyl chloride up to 1200 K
• Analysis of gaseous ammonia (NH${}_3$) absorption in the visible spectrum of Jupiter - Update
• Ions in the Thermosphere of Exoplanets: Observable Constraints Revealed by Innovative Laboratory Experiments
• Machine Learning for Observables: Reactant to Product State Distributions for Atom-Diatom Collisions
• Hot exoplanetary atmospheres in 3D
• PyExoCross: a Python program for generating spectra and cross-sections from molecular line lists
• Cross-sections for heavy atmospheres: H${}_2$O self-broadening
• Molecular line shape parameters for exoplanetary atmospheric applications
• ARES VI: Viability of one-dimensional retrieval models for transmission spectroscopy characterization of exo-atmospheres in the era of JWST and Ariel
• Unraveling the non-equilibrium chemistry of the temperate sub-Neptune K2-18 b
• ExoMolHR: A Relational Database of Empirical High-Resolution Molecular Spectra
• Filters for NIR astronomical photometry: comparison of commercial IRWG filters and designs using OpenFilters