Spatially-resolving the terminator: Variation of Fe, temperature and winds in WASP-76 b across planetary limbs and orbital phase

Abstract

Exoplanet atmospheres are inherently three-dimensional systems in which thermal/chemical variation and winds can strongly influence spectra. Recently, the ultra-hot Jupiter WASP-76 b has shown evidence for condensation and asymmetric Fe absorption with time. However, it is currently unclear whether these asymmetries are driven by chemical or thermal differences between the two limbs, as precise constraints on variation in these have remained elusive due to the challenges of modelling these dynamics in a Bayesian framework. To address this we develop a new model, HyDRA-2D, capable of simultaneously retrieving morning and evening terminators with day-night winds. We explore variations in Fe, temperature profile, winds and opacity deck with limb and orbital phase using VLT/ESPRESSO observations of WASP-76 b. We find Fe is more prominent on the evening for the last quarter of the transit, with $\log (X_{\mathrm{Fe}})={-4.03}_{-0.31}^{+0.28}$, but the morning shows a lower abundance with a wider uncertainty, $\log (X_{\mathrm{Fe}})={-4.59}_{-1.0}^{+0.85}$, driven by degeneracy with the opacity deck and the stronger evening signal. We constrain 0.1 mbar temperatures ranging from $2950_{-156}^{+111}$ K to $2615_{-275}^{+266}$ K, with a trend of higher temperatures for the more irradiated atmospheric regions. We also constrain a day-night wind speed of $9.8_{-1.1}^{+1.2}$ km/s for the last quarter, higher than $5.9_{-1.1}^{+1.5}$ km/s for the first, in line with general circulation models. We find our new spatially- and phase-resolved treatment is statistically favoured by 4.9$\sigma$ over traditional 1D-retrievals, and thus demonstrate the power of such modelling for robust constraints with current and future facilities.

18 pages, 15 figures, accepted for publication in MNRAS

References in corpus (52)

• Molecfit: A general tool for telluric absorption correction. I. Method and application to ESO instruments
• The imprint of exoplanet formation history on observable present-day spectra of hot Jupiters
• Atomic and Molecular Opacities for Brown Dwarf and Giant Planet Atmospheres
• Nightside condensation of iron in an ultra-hot giant exoplanet
• A Sub-Neptune Exoplanet with a Low-Metallicity Methane-Depleted Atmosphere and Mie-Scattering Clouds
• Mass-Metallicity Trends in Transiting Exoplanets from Atmospheric Abundances of H${}_2$O, Na, and K
• A spectral survey of an ultra-hot Jupiter: Detection of metals in the transmission spectrum of KELT-9 b
• Detection of Fe I in the atmosphere of the ultra-hot Jupiter WASP-121b, and a new likelihood-based approach for Doppler-resolved spectroscopy
• A consistent retrieval analysis of 10 Hot Jupiters observed in transmission
• A solar C/O and sub-solar metallicity in a hot Jupiter atmosphere
• Five carbon- and nitrogen-bearing species in a hot giant planet's atmosphere
• H2O abundances in the atmospheres of three hot Jupiters
• The Atmospheric Circulation of Ultra-hot Jupiters
• Neutral Iron Emission Lines From The Day-side Of KELT-9b -- The GAPS Programme With HARPS-N At TNG XX
• GENESIS: New Self-Consistent Models of Exoplanetary Spectra
• Hot Exoplanet Atmospheres Resolved with Transit Spectroscopy (HEARTS) - II. A broadened sodium feature on the ultra-hot giant WASP-76b
• Where is the Water? Jupiter-like C/H ratio but strong H${}_2$O depletion found on $\tau$ Boötis b using SPIRou
• Retrieval of Exoplanet Emission Spectra with HyDRA
• ESPRESSO high resolution transmission spectroscopy of WASP-76b
• TESS Transit Timing of Hundreds of Hot Jupiters
• PLATON II: New Capabilities And A Comprehensive Retrieval on HD 189733b Transit and Eclipse Data
• A New Window into Planet Formation and Migration: Refractory-to-Volatile Elemental Ratios in Ultra-hot Jupiters
• Decomposing the Iron Cross-Correlation Signal of the Ultra-Hot Jupiter WASP-76b in Transmission using 3D Monte-Carlo Radiative Transfer
• On degeneracies in retrievals of exoplanetary transmission spectra
• An Atomic Spectral Survey of WASP-76b: Resolving Chemical Gradients and Asymmetries
• Detection of neutral atomic species in the ultra-hot jupiter WASP-121b
• Search for water vapor in the high-resolution transmission spectrum of HD189733b in the visible
• New Avenues for Thermal Inversions in hot Jupiters
• An emission spectrum for WASP-121b measured across the 0.8-1.1 micron wavelength range using the Hubble Space Telescope
• Non-detection of TiO and VO in the atmosphere of WASP-121b using high-resolution spectroscopy
• Relative abundance constraints from high-resolution optical transmission spectroscopy of WASP-121b, and a fast model-filtering technique for accelerating retrievals
• ARES I: WASP-76 b, A Tale of Two HST Spectra
• Wind of Change: retrieving exoplanet atmospheric winds from high-resolution spectroscopy
• Confirmation of Asymmetric Iron Absorption in WASP-76b with HARPS
• Molecular Cross Sections for High Resolution Spectroscopy of Super Earths, Warm Neptunes and Hot Jupiters
• Aurora: A Generalised Retrieval Framework for Exoplanetary Transmission Spectra
• A Significant Increase in Detection of High-Resolution Emission Spectra Using a Three-Dimensional Atmospheric Model of a Hot Jupiter
• An inventory of atomic species in the atmosphere of WASP-121b using UVES high-resolution spectroscopy
• Into the Storm: Diving into the winds of the ultra hot Jupiter WASP-76 b with HARPS and ESPRESSO
• No umbrella needed: Confronting the hypothesis of iron rain on WASP-76b with post-processed general circulation models
• HyDRA-H: Simultaneous Hybrid Retrieval of Exoplanetary Emission Spectra
• Detection of OH in the ultra-hot Jupiter WASP-76b
• ExoClock project II: A large-scale integrated study with 180 updated exoplanet ephemerides
• Seeing above the Clouds with High Resolution Spectroscopy
• On Atmospheric Retrievals of Exoplanets with Inhomogeneous Terminators
• The Hubble PanCET program: Transit and Eclipse Spectroscopy of the Strongly Irradiated Giant Exoplanet WASP-76b
• An analytical formalism accounting for clouds and other "surfaces" for exoplanet transmission spectroscopy
• A Universal Cloud Composition on the Nightsides of Hot Jupiters
• Assessing Spectra and Thermal Inversions due to TiO in Hot Jupiter Atmospheres
• H- and Dissociation in Ultra-hot Jupiters: A Retrieval Case Study of WASP-18b
• HST/STIS transmission spectrum of the ultra-hot Jupiter WASP-76 b confirms the presence of sodium in its atmosphere
• All along the line of sight: a closer look at opening angles and absorption regions in the atmospheres of transiting exoplanets

Cited by in corpus (28)

• Vanadium oxide and a sharp onset of cold-trapping on a giant exoplanet
• Retrieval survey of metals in six ultra-hot Jupiters: Trends in chemistry, rain-out, ionisation and atmospheric dynamics
• Detection of a high-velocity sodium feature on the ultra-hot Jupiter WASP-121 b
• Evidence for Morning-to-Evening Limb Asymmetry on the Cool Low-Density Exoplanet WASP-107b
• The PEPSI Exoplanet Transit Survey (PETS). II. A Deep Search for Thermal Inversion Agents in KELT-20 b/MASCARA-2 b with Emission and Transmission Spectroscopy
• CRIRES${}^{+}$ transmission spectroscopy of WASP-127b. Detection of the resolved signatures of a supersonic equatorial jet and cool poles in a hot planet
• Unifying High- and Low-resolution Observations to Constrain the Dayside Atmosphere of KELT-20b/MASCARA-2b
• Diagnosing limb asymmetries in hot and ultra-hot Jupiters with high-resolution transmission spectroscopy
• An atlas of resolved spectral features in the transmission spectrum of WASP-189 b with MAROON-X
• Magnetic Effects and 3D Structure in Theoretical High-Resolution Transmission Spectra of Ultrahot Jupiters: the Case of WASP-76b
• High-resolution atmospheric retrievals of WASP-76b transmission spectroscopy with ESPRESSO: Monitoring limb asymmetries across multiple transits
• Titanium chemistry of WASP-121 b with ESPRESSO in 4-UT mode
• The atmospheric composition of the ultra-hot Jupiter WASP-178 b observed with ESPRESSO
• A Panchromatic Characterization of the Evening and Morning Atmosphere of WASP-107 b: Composition and Cloud Variations, and Insight into the Effect of Stellar Contamination
• Tracing the formation and migration history: molecular signatures in the atmosphere of misaligned hot Jupiter WASP-94Ab using JWST NIRSpec/G395H
• Detection of atmospheric species and dynamics in the bloated hot Jupiter WASP-172~b with ESPRESSO
• 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
• ATMOSPHERIX: III- Estimating the C/O ratio and molecular dynamics at the limbs of WASP-76 b with SPIRou
• A Time-Resolved High-Resolution Spectroscopic Analysis of Ionized Calcium and Dynamical Processes in the Ultra-Hot Jupiter HAT-P-70 b
• Probing Two-dimensional Asymmetries of an Exoplanet Atmosphere from Chromatic Transit Variation
• 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
• Open Source High-Resolution Exoplanet Atmosphere Retrievals with POSEIDON
• PEPSI Investigation, Retrieval, and Atlas of Numerous Giant Atmospheres (PIRANGA). IV. High-Resolution Phased-Resolved Spectroscopy of The Ultra Hot Jupiter KELT-20 b
• Assessing robustness and bias in 1D retrievals of 3D Global Circulation Models at high spectral resolution: a WASP-76 b simulation case study in emission
• Atmospheric asymmetries in WASP-121 b revealed by rotational transits detected with JWST
• Horizontal transport as a source of disequilibrium chemistry on the nightside of a hot exoplanet
• First Results from WINERED: Detection of Emission Lines from Neutral Iron and a Combined Set of Trace Species on the Dayside of WASP-189 b