A new look into the atmospheric composition of WASP-39 b

Abstract

Being one of the first exoplanets observed by the James Webb Space Telescope, WASP-39 b has become an iconic target and many transit spectra recorded with different instruments (NIRISS, NIRCAM, NIRSpec G395H, NIRSpec PRISM and MIRI) are currently available, allowing in-depth studies of its atmosphere. We present here a novel approach to interpret WASP-39 b's transit spectroscopic data, consisting of a multi-step process where ab initio equilibrium chemistry models and blind retrievals are used iteratively to find physically robust, optimal solutions. Following this approach, we have identified a new scenario to explain WASP-39 b's atmospheric composition, in which silicon-based chemistry plays a major role. In this scenario, SiO may explain the spectral absorption at 4.1 $\mu$m, currently interpreted as being due to SO${}_2$. SiO and the other gas species identified by the retrieval models, i.e. H${}_2$O, CO${}_2$, Na and K, are consistent with an atmosphere in chemical equilibrium with a temperature-pressure profile constrained by H${}_2$O and CO${}_2$ absorption bands. In addition, silicate clouds and hazes can produce the spectral features observed by MIRI in the spectral window 5-12 $\mu$m. While we advocate the need for more data, possibly at higher spectral resolution, to confirm our results for WASP-39 b's atmospheric composition, we highlight a refined atmospheric retrieval strategy with pre-selection and post-reconstruction to guide the next generation of transit spectroscopy.

32 pages, 22 figures, published in ApJ

References in corpus (50)

• Array Programming with NumPy
• The Astropy Project: Sustaining and Growing a Community-oriented Open-source Project and the Latest Major Release (v5.0) of the Core Package
• The Science Performance of JWST as Characterized in Commissioning
• Early Release Science of the exoplanet WASP-39b with JWST NIRSpec PRISM
• Early Release Science of the Exoplanet WASP-39b with JWST NIRSpec G395H
• Photochemically-produced SO${}_2$ in the atmosphere of WASP-39b
• ExoMol molecular line lists XXXV: a rotation-vibration line list for hot ammonia
• ExoMol molecular line lists - XVI: The rotation-vibration spectrum of hot H${}_2$S
• Early Release Science of the exoplanet WASP-39b with JWST NIRISS
• ExoMol line lists XVIII. The high temperature spectrum of VO
• ExoMol line lists -- XXXIX. Ro-vibrational molecular line list for CO${}_2$
• Early Release Science of the exoplanet WASP-39b with JWST NIRCam
• Identification of carbon dioxide in an exoplanet atmosphere
• The Complete transmission spectrum of WASP-39b with a precise water constraint
• A reflective, metal-rich atmosphere for GJ 1214b from its JWST phase curve
• Eureka!: An End-to-End Pipeline for JWST Time-Series Observations
• Exploring Biases of Atmospheric Retrievals in Simulated JWST Transmission Spectra of Hot Jupiters
• VLT FORS2 comparative transmission spectroscopy: Detection of Na in the atmosphere of WASP-39b from the ground
• Optical constants of refractory oxides at high temperatures
• Chemical equilibrium in AGB atmospheres: Successes, failures, and prospects for small molecules, clusters, and condensates
• Sulphur dioxide in the mid-infrared transmission spectrum of WASP-39b
• Five key exoplanet questions answered via the analysis of 25 hot Jupiter atmospheres in eclipse
• Helios-r2 -- A new Bayesian, open-source retrieval model for brown dwarfs and exoplanet atmospheres
• ExoMol molecular line lists - XXIII: spectra of PO and PS
• Awesome SOSS: Transmission Spectroscopy of WASP-96b with NIRISS/SOSS
• Analysis of a JWST NIRSpec Lab Time Series: Characterizing Systematics, Recovering Exoplanet Transit Spectroscopy, and Constraining a Noise Floor
• ExoMol line lists -- XLIV. IR and UV line list for silicon monoxide (SiO)
• A Benchmark JWST Near-Infrared Spectrum for the Exoplanet WASP-39b
• ExoMol molecular line lists X: The spectrum of sodium hydride
• Signs of strong Na and K absorption in the transmission spectrum of WASP-103b
• A comparison of chemical models of exoplanet atmospheres enabled by TauREx 3.1
• Exoplanet Spectroscopy with JWST NIRISS: Diagnostics and Case Studies
• ATOCA: an algorithm to treat order contamination. Application to the NIRISS SOSS mode
• ExoMol line lists -- XLI. High-temperature molecular line lists for the alkali metal hydroxides KOH and NaOH
• Data availability and requirements relevant for the Ariel space mission and other exoplanet atmosphere applications
• Detection of carbon monoxide's 4.6 micron fundamental band structure in WASP-39b's atmosphere with JWST NIRSpec G395H
• Origin and extent of the opacity challenge for atmospheric retrievals of WASP-39 b
• A Concise Treatise on Converting Stellar Mass Fractions to Abundances to Molar Ratios
• Planet Mass and Metallicity: The Exoplanets and Solar System Connection
• Day-night transport induced chemistry and clouds on WASP-39b I: Gas-phase composition
• YunMa: Enabling Spectral Retrievals of Exoplanetary Clouds
• Knobs and dials of retrieving JWST transmission spectra. I. The importance of p-T profile complexity
• Cloud and Haze Parameterization in Atmospheric Retrievals: Insights from Titan's Cassini Data and JWST Observations of Hot Jupiters
• Constraining the formation of WASP-39b using JWST transit spectroscopy
• A Population Analysis of 20 Exoplanets Observed from the Optical to the Near-infrared Wavelengths with HST: Evidence for Widespread Stellar Contamination
• Comparing transit spectroscopy pipelines at the catalogue level: evidence for systematic differences
• The effect of spectroscopic binning on atmospheric retrievals
• Inclusion of sulfur chemistry in a validated C/H/O/N chemical network: identification of key C/S coupling pathways
• The role of cloud particle properties on WASP-39b transmission spectrum based on JWST/NIRSpec observations
• Probing Two-dimensional Asymmetries of an Exoplanet Atmosphere from Chromatic Transit Variation