A unique hot Jupiter spectral sequence with evidence for compositional diversity

Abstract

The emergent spectra of close-in, giant exoplanets ("hot Jupiters") are expected to be distinct from those of self-luminous objects with similar effective temperatures because hot Jupiters are primarily heated from above by their host stars rather than internally from the release of energy from their formation. Theoretical models predict a continuum of dayside spectra for hot Jupiters as a function of irradiation level, with the coolest planets having absorption features in their spectra, intermediate-temperature planets having emission features due to thermal inversions, and the hottest planets having blackbody-like spectra due to molecular dissociation and continuum opacity from the H- ion. Absorption and emission features have been detected in the spectra of a number of individual hot Jupiters, and population-level trends have been observed in photometric measurements. However, there has been no unified, population-level study of the thermal emission spectra of hot Jupiters such as has been done for cooler brown dwarfs and transmission spectra of hot Jupiters. Here we show that hot Jupiter secondary eclipse spectra centered around a water absorption band at 1.4 microns follow a common trend in water feature strength with temperature. The observed trend is broadly consistent with model predictions for how the thermal structures of solar-composition planets vary with irradiation level. Nevertheless, the ensemble of planets exhibits some degree of scatter around the mean trend for solar composition planets. The spread can be accounted for if the planets have modest variations in metallicity and/or elemental abundance ratios, which is expected from planet formation models. (abridged abstract)

24 pages, 8 figures, published in Nature Astronomy

References in corpus (66)

• SciPy 1.0--Fundamental Algorithms for Scientific Computing in Python
• emcee: The MCMC Hammer
• The NumPy array: a structure for efficient numerical computation
• A new extensive library of PHOENIX stellar atmospheres and synthetic spectra
• batman: BAsic Transit Model cAlculatioN in Python
• A continuum from clear to cloudy hot-Jupiter exoplanets without primordial water depletion
• Clouds in the atmosphere of the super-Earth exoplanet GJ 1214b
• The orbital motion, absolute mass, and high-altitude winds of exoplanet HD209458b
• Precipitating Condensation Clouds in Substellar Atmospheres
• A Unified Theory for the Atmospheres of the Hot and Very Hot Jupiters: Two Classes of Irradiated Atmospheres
• The Evolution of L and T Dwarfs in Color-Magnitude Diagrams
• Abundances of the elements in the solar system
• New Grids of ATLAS9 Model Atmospheres
• A Possible Bifurcation in Atmospheres of Strongly Irradiated Stars and Planets
• A Precise Water Abundance Measurement for the Hot Jupiter WASP-43b
• The imprint of exoplanet formation history on observable present-day spectra of hot Jupiters
• Characterizing transiting exoplanet atmospheres with JWST
• 3D mixing in hot Jupiter atmospheres. I. application to the day/night cold trap in HD 209458b
• The Flat Transmission Spectrum of the Super-Earth GJ1214b from Wide Field Camera 3 on the Hubble Space Telescope
• From thermal dissociation to condensation in the atmospheres of ultra hot Jupiters: WASP-121b in context
• A population study of gaseous exoplanets
• H- Opacity and Water Dissociation in the Dayside Atmosphere of the Very Hot Gas Giant WASP-18 b
• Retrieving Temperatures and Abundances of Exoplanet Atmospheres with High-Resolution Cross-Correlation Spectroscopy
• Extremely Irradiated Hot Jupiters: Non-Oxide Inversions, H- Opacity, and Thermal Dissociation of Molecules
• The 2020 release of the ExoMol database: molecular line lists for exoplanet and other hot atmospheres
• Global Climate and Atmospheric Composition of the Ultra-Hot Jupiter WASP-103b from HST and Spitzer Phase Curve Observations
• Atmospheric Signatures of Giant Exoplanet Formation by Pebble Accretion
• Balancing the Energy Budget of Short-Period Giant Planets: Evidence for Reflective Clouds and Optical Absorbers
• Retrieval of atmospheric properties of cloudy L dwarfs
• The Atmospheres of Earth-like Planets after Giant Impact Events
• The Peculiar Atmospheric Chemistry of KELT-9b
• The Intrinsic Temperature and Radiative-Convective Boundary Depth in the Atmospheres of Hot Jupiters
• The cloudy shape of hot Jupiter thermal phase curves
• Atmospheric Dynamics of Hot Giant Planets and Brown Dwarfs
• The UK Met Office GCM with a sophisticated radiation scheme applied to the hot Jupiter HD 209458b
• Spitzer Phase Curves of KELT-1b and the Signatures of Nightside Clouds in Thermal Phase Observations
• A HST/WFC3 Thermal Emission Spectrum of the Hot Jupiter HAT-P-7b
• Statistical Characterization of Hot Jupiter Atmospheres using Spitzer's Secondary Eclipses
• Photolytic Hazes in the Atmosphere of 51 Eri b
• Clouds in Three-Dimensional Models of Hot Jupiters Over a Wide Range of Temperatures I: Thermal Structures and Broadband Phase Curve Predictions
• Connecting planet formation and astrochemistry: A main sequence for C/O in hot-exoplanetary atmospheres
• Uniformly hot nightside temperatures on short-period gas giants
• Marginalising instrument systematics in HST WFC3 transit lightcurves
• ARES I: WASP-76 b, A Tale of Two HST Spectra
• A Uniform Retrieval Analysis of Ultracool Dwarfs. III. Properties of Y-Dwarfs
• The Influence of Host Star Spectral Type on Ultra-Hot Jupiter Atmospheres
• EXOPLINES: Molecular Absorption Cross-Section Database for Brown Dwarf and Giant Exoplanet Atmospheres
• A transition between the hot and the ultra-hot Jupiter atmospheres
• Evidence for Atmospheric Cold-trap Processes in the Noninverted Emission Spectrum of Kepler-13Ab Using HST/WFC3
• Confirmation of water emission in the dayside spectrum of the ultrahot Jupiter WASP-121b
• Exploring Exoplanet Cloud Assumptions in \textit{JWST} Transmission Spectra
• Spitzer Secondary Eclipse Observations of Five Cool Gas Giant Planets and Empirical Trends in Cool Planet Emission Spectra
• Ground- and Space-based Detection of the Thermal Emission Spectrum of the Transiting Hot Jupiter KELT-2Ab
• Secondary eclipse observations for seven hot-Jupiters from the Anglo-Australian Telescope
• Spitzer and z' Secondary Eclipse Observations of the Highly Irradiated Transiting Brown Dwarf KELT-1b
• ARES III: Unveiling the Two Faces of KELT-7 b with HST WFC3
• The Hubble PanCET program: Transit and Eclipse Spectroscopy of the Strongly Irradiated Giant Exoplanet WASP-76b
• Hubble PanCET: An isothermal day-side atmosphere for the bloated gas-giant HAT-P-32Ab
• The Influence of H2O Pressure Broadening in High Metallicity Exoplanet Atmospheres
• Cloud Atlas: Hubble Space Telescope Near-Infrared Spectral Library of Brown Dwarfs, Planetary-mass companions, and hot Jupiters
• Colour-magnitude diagrams of transiting Exoplanets - II. A larger sample from photometric distances
• Disentangling Hot Jupiters formation location from their chemical composition
• A multiplicity study of transiting exoplanet host stars. II. Revised properties of transiting planetary systems with companions
• How Does Thermal Scattering Shape the Infrared Spectra of Cloudy Exoplanets? A Theoretical Framework and Consequences for Atmospheric Retrievals in the JWST era
• Colour-magnitude diagrams of transiting Exoplanets -- III. A public code, nine strange planets, and the role of Phosphine
• Colour-colour and colour-magnitude diagrams for Hot Jupiters

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