Seasonal Changes in the Atmosphere of HD 80606b Observed with JWST's NIRSpec/G395H

Abstract

High-eccentricity gas giant planets serve as unique laboratories for studying the thermal and chemical properties of H/He-dominated atmospheres. One of the most extreme cases is HD 80606b -- a hot Jupiter orbiting a sun-like star with an eccentricity of $0.93$ -- which experiences an increase in incident flux of nearly three orders of magnitude as the star-planet separation decreases from $0.88\mathrm{AU}$ at apoastron to $0.03\mathrm{AU}$ at periastron. We observed the planet's periastron passage using \emph{JWST}'s NIRSpec/G395H instrument ($2.8-5.2\mu \mathrm{m}$) during a $21\mathrm{hr}$ window centered on the eclipse. We find that, as the planet passes through periastron, its emission spectrum transitions from a featureless blackbody to one in which CO, CH${}_4$, and H${}_2$O absorption features are visible. We detect CH${}_4$ during post-periapse phases at $4.1-10.7\sigma$ depending on the phase and on whether a flux offset is included to account for NRS1 detector systematics. Following periapse, H${}_2$O and CO are also detected at $4.2-5.5\sigma$ and $3.7-4.4\sigma$, respectively. Furthermore, we rule out the presence of a strong temperature inversion near the IR photosphere based on the lack of obvious emission features throughout the observing window. General circulation models had predicted an inversion during periapse passage. Our study demonstrates the feasibility of studying hot Jupiter atmospheres using partial phase curves obtained with NIRSpec/G395H.

arXiv comment26 pages, 18 figures, 2 tables. Accepted by The Astronomical Journal

References in corpus (54)

• SciPy 1.0--Fundamental Algorithms for Scientific Computing in Python
• Array Programming with NumPy
• Astropy: A Community Python Package for Astronomy
• emcee: The MCMC Hammer
• The Astropy Project: Building an inclusive, open-science project and status of the v2.0 core package
• The Astropy Project: Sustaining and Growing a Community-oriented Open-source Project and the Latest Major Release (v5.0) of the Core Package
• The Transiting Exoplanet Survey Satellite
• batman: BAsic Transit Model cAlculatioN in Python
• petitRADTRANS: a Python radiative transfer package for exoplanet characterization and retrieval
• On the radiative equilibrium of irradiated planetary atmospheres
• Disequilibrium Carbon, Oxygen, and Nitrogen Chemistry in the Atmospheres of HD 189733b and HD 209458b
• Neglected Clouds in T and Y Dwarf Atmospheres
• emcee v3: A Python ensemble sampling toolkit for affine-invariant MCMC
• Early Release Science of the Exoplanet WASP-39b with JWST NIRSpec G395H
• Atmospheric Chemistry in Giant Planets, Brown Dwarfs, and Low-Mass Dwarf Stars III. Iron, Magnesium, and Silicon
• Search for Carbon Monoxide in the atmosphere of the Transiting Exoplanet HD189733b
• Observing transiting planets with JWST -- Prime targets and their synthetic spectral observations
• HD 80606 b, a planet on an extremely elongated orbit
• The HST PanCET Program: Exospheric Mg II and Fe II in the Near-UV transmission spectrum of WASP-121b using Jitter Decorrelation
• Orbital Phase Variations of the Eccentric Giant Planet HAT-P-2b
• High Tide or Riptide on the Cosmic Shoreline? A Water-Rich Atmosphere or Stellar Contamination for the Warm Super-Earth GJ~486b from JWST Observations
• Spitzer Phase Curve Constraints for WASP-43b at 3.6 and 4.5 microns
• Eureka!: An End-to-End Pipeline for JWST Time-Series Observations
• Photometric and spectroscopic detection of the primary transit of the 111-day-period planet HD 80606 b
• A Model for Thermal Phase Variations of Circular and Eccentric Exoplanets
• On Correlated-noise Analyses Applied To Exoplanet Light Curves
• Beyond Equilibrium Temperature: How the Atmosphere/Interior Connection Affects the Onset of Methane, Ammonia, and Clouds in Warm Transiting Giant Planets
• Deciphering the Atmospheric Composition of WASP-12b: A Comprehensive Analysis of its Dayside Emission
• Observation of the full 12-hour-long transit of the exoplanet HD80606b. Warm-Spitzer photometry and SOPHIE spectroscopy
• Three-dimensional atmospheric circulation of hot Jupiters on highly eccentric orbits
• Spin-orbit misalignment in the HD80606 planetary system
• The Transit Ingress and the Tilted Orbit of the Extraordinarily Eccentric Exoplanet HD 80606b
• Detection of a transit by the planetary companion of HD 80606
• Hydrodynamic Simulations of Unevenly Irradiated Jovian Planets
• Analysis of a JWST NIRSpec Lab Time Series: Characterizing Systematics, Recovering Exoplanet Transit Spectroscopy, and Constraining a Noise Floor
• Molecular Cross Sections for High Resolution Spectroscopy of Super Earths, Warm Neptunes and Hot Jupiters
• ACCESS & LRG-BEASTS: a precise new optical transmission spectrum of the ultrahot Jupiter WASP-103b
• The Pyrat Bay Framework for Exoplanet Atmospheric Modeling: A Population Study of Hubble/WFC3 Transmission Spectra
• Photometric Detection of a Transit of HD 80606b
• High atmospheric metal enrichment for a Saturn-mass planet
• Chemical Timescales in the Atmospheres of Highly Eccentric Exoplanets
• LRG-BEASTS III: Ground-based transmission spectrum of the gas giant orbiting the cool dwarf WASP-80
• Early Insights for Atmospheric Retrievals of Exoplanets using JWST Transit Spectroscopy
• Probing potassium in the atmosphere of HD 80606b with tunable filter transit spectrophotometry from the Gran Telescopio Canarias
• Searching for the origin of the Ehrenreich effect in ultra-hot Jupiters: Evidence for strong C/O gradients in the atmosphere of WASP-76b?
• Direct Measure of Radiative and Dynamical Properties of an Exoplanet Atmosphere
• Detectability of Exoplanet Periastron Passage in the Infra-Red
• Variable Irradiation on 1D Cloudless Eccentric Exoplanet Atmospheres
• Exoplanetary Transit Constraints Based Upon Secondary Eclipse Observations
• Thermal Phase Curves of XO-3b: an Eccentric Hot Jupiter at the Deuterium Burning Limit
• Utilizing a global network of telescopes to update the ephemeris for the highly eccentric planet HD 80606 b and to ensure the efficient scheduling of JWST
• Photodissociation and induced chemical asymmetries on ultra-hot gas giants. A case study of HCN on WASP-76 b
• The Climate and Compositional Variation of the Highly Eccentric Planet HD 80606 b -- the rise and fall of carbon monoxide and elemental sulfur
• Examining the detectability of ringing on highly eccentric exoplanets

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