The Hubble PanCET program: Transit and Eclipse Spectroscopy of the Strongly Irradiated Giant Exoplanet WASP-76b

Abstract

Ultra-hot Jupiters with equilibrium temperature greater than 2000K are uniquely interesting targets as they provide us crucial insights into how atmospheres behave under extreme conditions. This class of giant planets receives intense radiation from their host star and usually has strongly irradiated and highly inflated atmospheres. At such high temperature, cloud formation is expected to be suppressed and thermal dissociation of water vapor could occur. We observed the ultra-hot Jupiter WASP-76b with 7 transits and 5 eclipses using the Hubble Space Telescope (HST) and $Spitzer$ for a comprehensive study of its atmospheric chemical and physical processes. We detect TiO and H${}_2$O absorption in the optical and near-infrared transit spectrum. Additional absorption by a number of neutral and ionized heavy metals like Fe, Ni, Ti, and SiO help explain the short wavelength transit spectrum. The secondary eclipse spectrum shows muted water feature but a strong CO emission feature in Spitzer's 4.5 $\mu$m band indicating an inverted temperature pressure profile. We analyzed both the transit and emission spectrum with a combination of self-consistent PHOENIX models and retrieval models (ATMO $\&$ PLATON). Both spectra are well fitted by the self-consistent PHOENIX forward atmosphere model in chemical and radiative equilibrium at solar metallicity, adding to the growing evidence that both TiO/VO and NUV heavy metals opacity are prominent NUV-optical opacity sources in the stratospheres of ultra-hot Jupiters.

28 pages, 18 figures, 9 tables, accepted by AJ

References in corpus (27)

• Detection of Thermal Emission from an Extrasolar Planet
• A giant comet-like cloud of hydrogen escaping the warm Neptune-mass exoplanet GJ 436b
• A Precise Water Abundance Measurement for the Hot Jupiter WASP-43b
• Thermal structure of an exoplanet atmosphere from phase-resolved emission spectroscopy
• Nightside condensation of iron in an ultra-hot giant exoplanet
• Spitzer Secondary Eclipses of the Dense, Modestly-irradiated, Giant Exoplanet HAT-P-20b Using Pixel-Level Decorrelation
• Water Vapour Absorption in the Clear Atmosphere of an exo-Neptune
• An ultrahot gas-giant exoplanet with a stratosphere
• Fingering convection and cloudless models for cool brown dwarf atmospheres
• HST hot-Jupiter transmission spectral survey: detection of potassium in WASP-31b along with a cloud deck and Rayleigh scattering
• HAT-P-26b: A Neptune-Mass Exoplanet with a Well Constrained Heavy Element Abundance
• Spitzer Phase Curve Constraints for WASP-43b at 3.6 and 4.5 microns
• The Effects of Consistent Chemical Kinetics Calculations on the Pressure-Temperature Profiles and Emission Spectra of Hot Jupiters
• H2O abundances in the atmospheres of three hot Jupiters
• Re-Evaluating WASP-12b: Strong Emission at 2.315 micron, Deeper Occultations, and an Isothermal Atmosphere
• HST hot-Jupiter transmission spectral survey: Haze in the atmosphere of WASP-6b
• Hot Exoplanet Atmospheres Resolved with Transit Spectroscopy (HEARTS) - II. A broadened sodium feature on the ultra-hot giant WASP-76b
• Statistical Analysis of Hubble/WFC3 Transit Spectroscopy of Extrasolar Planets
• New Avenues for Thermal Inversions in hot Jupiters
• Confirmation of WASP-107b's extended Helium atmosphere with Keck II/NIRSPEC
• ARES I: WASP-76 b, A Tale of Two HST Spectra
• The Influence of Host Star Spectral Type on Ultra-Hot Jupiter Atmospheres
• An Eccentric Massive Jupiter Orbiting a Sub-Giant on a 9.5 Day Period Discovered in the Transiting Exoplanet Survey Satellite Full Frame Images
• Parameters and Predictions for the Long-Period Transiting Planet HD 17156b
• UV Exoplanet Transmission Spectral Features as Probes of Metals and Rainout
• A multiplicity study of transiting exoplanet host stars. I. High-contrast imaging with VLT/SPHERE
• HST/STIS transmission spectrum of the ultra-hot Jupiter WASP-76 b confirms the presence of sodium in its atmosphere

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• A Comprehensive Analysis of WASP-17b's Transmission Spectrum from Space-Based Observations
• Strong H${}_2$O and CO emission features in the spectrum of KELT-20b driven by stellar UV irradiation
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• Confirmation of Water Absorption in the Thermal Emission Spectrum of the Hot Jupiter WASP-77Ab with HST/WFC3
• Magnetic Effects and 3D Structure in Theoretical High-Resolution Transmission Spectra of Ultrahot Jupiters: the Case of WASP-76b
• The metal-poor atmosphere of a Neptune/Sub-Neptune planet progenitor
• ThERESA: Three-Dimensional Eclipse Mapping with Application to Synthetic JWST Data
• A strong H- opacity signal in the near-infrared emission spectrum of the ultra-hot Jupiter KELT-9b
• Photodissociation and induced chemical asymmetries on ultra-hot gas giants. A case study of HCN on WASP-76 b
• ESPRESSO reveals blueshifted neutral iron emission lines on the dayside of WASP-76 b
• Probing Na in giant exoplanets with ESPRESSO and 3D NLTE stellar spectra
• ATMOSPHERIX: III- Estimating the C/O ratio and molecular dynamics at the limbs of WASP-76 b with SPIRou
• Conditions for radiative zones in the molecular hydrogen envelope of Jupiter and Saturn: The role of alkali metals
• The Hubble PanCET program: Transit and Eclipse Spectroscopy of the Hot Jupiter WASP-74b
• The Hubble PanCET program: Emission spectrum of hot Jupiter HAT-P-41b
• Lessons from Hubble and Spitzer: 1D Self-Consistent Model Grids for 19 Hot Jupiter Emission Spectra
• Detection of Na in the atmosphere of the hot Jupiter HAT-P-55b
• The GAPS Programme at TNG. LXIX.The Dayside of WASP-76b revealed by GIANO-B, HARPS-N and ESPRESSO: Evidence for Three-Dimensional Atmospheric Effects
• Magnetic Drag and 3-D Effects in Theoretical High-Resolution Emission Spectra of Ultrahot Jupiters: the Case of WASP-76b
• Patchy nightside clouds on ultra-hot Jupiters: General Circulation Model simulations with radiatively active cloud tracers
• Effects of the internal temperature on vertical mixing and on cloud structures in Ultra Hot Jupiters
• Investigation of the upper atmosphere in ultra-hot Jupiter WASP-76 b with high-resolution spectroscopy