Emergent Spectral Fluxes of Hot Jupiters: an Abrupt Rise in Day Side Brightness Temperature Under Strong Irradiation

Abstract

We study the emergent spectral fluxes of transiting hot Jupiters, using secondary eclipses from Spitzer. To achieve a large and uniform sample, we have re-analyzed all secondary eclipses for all hot Jupiters observed by Spitzer at 3.6- and/or 4.5 microns. Our sample comprises 457 eclipses of 122 planets, including eclipses of 13 planets not previously published. We use these eclipse depths to calculate the spectral fluxes emergent from the exoplanetary atmospheres, and thereby infer temperature and spectral properties of hot Jupiters. We find that an abrupt rise in brightness temperature, similar to a phase change, occurs on the day side atmospheres of the population at an equilibrium temperature between 1714K and 1818K (99-percent confidence limits). The amplitude of the rise is 291 +/-49 Kelvins, and two viable causes are the onset of magnetic drag that inhibits longitudinal heat redistribution, and/or the rapid dissipation of day side clouds. We also study hot Jupiter spectral properties with respect to metallicity and temperature inversions. Models exhibiting 4.5 micron emission from temperature inversions reproduce our fluxes statistically for the hottest planets, but the transition to emission is gradual, not abrupt. The Spitzer fluxes are sensitive to metallicity for planets cooler than approximately 1200 Kelvins, and most of the hot Jupiter population falls between model tracks having solar to 30X-solar metallicity.

29 pages, 12 figures, 4 tables (3 are MR), accepted for the Astronomical Journal

References in corpus (56)

• New Grids of ATLAS9 Model Atmospheres
• The Broadband Infrared Emission Spectrum of the Exoplanet HD 189733b
• Spitzer Secondary Eclipses of the Dense, Modestly-irradiated, Giant Exoplanet HAT-P-20b Using Pixel-Level Decorrelation
• The 2020 release of the ExoMol database: molecular line lists for exoplanet and other hot atmospheres
• Mass-Metallicity Trends in Transiting Exoplanets from Atmospheric Abundances of H${}_2$O, Na, and K
• HD147506b: A Super-Massive Planet in an Eccentric Orbit Transiting a Bright Star
• A solar C/O and sub-solar metallicity in a hot Jupiter atmosphere
• Spitzer Phase Curve Constraints for WASP-43b at 3.6 and 4.5 microns
• Friends of Hot Jupiters II: No Correspondence Between Hot-Jupiter Spin-Orbit Misalignment and the Incidence of Directly Imaged Stellar Companions
• High temperature condensate clouds in super-hot Jupiter atmospheres
• New Analysis Indicates No Thermal Inversion in the Atmosphere of HD 209458b
• Balancing the Energy Budget of Short-Period Giant Planets: Evidence for Reflective Clouds and Optical Absorbers
• Friends of Hot Jupiters. IV. Stellar companions beyond 50 AU might facilitate giant planet formation, but most are unlikely to cause Kozai-Lidov migration
• Photometric and spectroscopic detection of the primary transit of the 111-day-period planet HD 80606 b
• Treatment of overlapping gaseous absorption with the correlated-k method in hot Jupiter and brown dwarf atmosphere models
• Atmospheric Characterization of the Hot Jupiter Kepler-13Ab
• The cloudy shape of hot Jupiter thermal phase curves
• Magnetic Effects in Hot Jupiter Atmospheres
• Hot Jupiters: Origins, Structure, Atmospheres
• Atmospheric Dynamics of Hot Giant Planets and Brown Dwarfs
• Spitzer Observations Confirm and Rescue the Habitable-Zone Super-Earth K2-18b for Future Characterization
• TESS Transit Timing of Hundreds of Hot Jupiters
• WASP-14b: 7.3 Mj transiting planet in an eccentric orbit
• Clouds in Three-Dimensional Models of Hot Jupiters Over a Wide Range of Temperatures I: Thermal Structures and Broadband Phase Curve Predictions
• Exploring the Effects of Active Magnetic Drag in a GCM of the Ultra-Hot Jupiter WASP-76b
• A unique hot Jupiter spectral sequence with evidence for compositional diversity
• Evidence of Three Mechanisms Explaining the Radius Anomaly of Hot Jupiters
• The Influence of Host Star Spectral Type on Ultra-Hot Jupiter Atmospheres
• Detection of Fe and evidence for TiO in the dayside emission spectrum of WASP-33b
• EXOPLINES: Molecular Absorption Cross-Section Database for Brown Dwarf and Giant Exoplanet Atmospheres
• Near-infrared Thermal Emission Detections of a number of hot Jupiters and the Systematics of Ground-based Near-infrared Photometry
• A transition between the hot and the ultra-hot Jupiter atmospheres
• Confirmation of water emission in the dayside spectrum of the ultrahot Jupiter WASP-121b
• A Comprehensive Reanalysis of $\text{Spitzer}$'s 4.5 $\mu$m Phase Curves, and the Phase Variations of the Ultra-hot Jupiters MASCARA-1b and KELT-16b
• Visible-light Phase Curves from the Second Year of the TESS Primary Mission
• Cloud property trends in hot and ultra-hot giant gas planets (WASP-43b, WASP-103b, WASP-121b, HAT-P-7b, and WASP-18b)
• A Lucky Imaging search for stellar companions to transiting planet host stars
• Detection of iron emission lines and a temperature inversion on the dayside of the ultra-hot Jupiter KELT-20b
• MPS-ATLAS: A fast all-in-one code for synthesising stellar spectra
• Detection of CO emission lines in the dayside atmospheres of WASP-33b and WASP-189b with GIANO
• A Universal Cloud Composition on the Nightsides of Hot Jupiters
• A New Analysis of 8 Spitzer Phase Curves and Hot Jupiter Population Trends: Qatar-1b, Qatar-2b, WASP-52b, WASP-34b, and WASP-140b
• Colour-magnitude diagrams of transiting Exoplanets - II. A larger sample from photometric distances
• Strong H${}_2$O and CO emission features in the spectrum of KELT-20b driven by stellar UV irradiation
• How Does Thermal Scattering Shape the Infrared Spectra of Cloudy Exoplanets? A Theoretical Framework and Consequences for Atmospheric Retrievals in the JWST era
• Spatially Resolved Modeling of Optical Albedos for a Sample of Six Hot Jupiters
• Spitzer Secondary Eclipse Depths with Multiple Intrapixel Sensitivity Correction Methods: Observations of WASP-13b, WASP-15b, WASP-16b, WASP-62b, and HAT-P-22b
• The Hubble PanCET Program: A Metal-rich Atmosphere for the Inflated Hot Jupiter HAT-P-41b
• Detection of the secondary eclipse of WASP-10b in the Ks-band
• Variable Irradiation on 1D Cloudless Eccentric Exoplanet Atmospheres
• The secondary transit of the hot Jupiter WASP-121b at 2 $\mu$m
• Shallowness of circulation in hot Jupiters -- Advancing the Ohmic dissipation model
• Why is it So Hot in Here? Exploring Population Trends in $\text{Spitzer}$ Thermal Emission Observations of Hot Jupiters using Planet-Specific Self-Consistent Atmospheric Models
• Thermal Phase Curves of XO-3b: an Eccentric Hot Jupiter at the Deuterium Burning Limit
• Colour-magnitude diagrams of transiting Exoplanets -- III. A public code, nine strange planets, and the role of Phosphine
• Trends in Spitzer Secondary Eclipses

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