Exploring Exoplanet Cloud Assumptions in JWST Transmission Spectra

Chuhong Mai, Michael R. Line

Research output: Contribution to journalArticle

Abstract

Clouds are ubiquitous in extrasolar planet atmospheres and are critical to our understanding of planetary climate and chemistry. They also represent one of the greater challenges to overcome when trying to interpret transit transmission spectra of exoplanet atmospheres as their presence can inhibit precise constraints on atmospheric composition and thermal properties. In this work, we take a phenomenological approach toward understanding (1) our ability to constrain bulk cloud properties and (2) the impact of clouds on constraining various atmospheric properties as obtained through transmission spectroscopy with the James Webb Space Telescope (JWST). We do this by exploring retrievals of atmospheric and cloud properties for a generic "hot Jupiter" as a function of signal-to-noise ratio (S/N), JWST observing modes, and four different cloud parameterizations. We find that most key atmospheric and cloud inferences can be well constrained in the wavelength range (λ = 0.6-11 μm), with NIRCam (λ = 2.5-5 μm) being critical in inferring atmospheric properties and NIRISS + MIRI (λ = 0.6-2.5, 5-11 μm) being necessary for good constraints on cloud parameters. However, constraining the cloud abundance and therefore the total cloud mass requires an observable cloud base in the transit geometry. While higher S/N observations can place tighter constraints on major parameters such as temperature, metallicity, and cloud sedimentation, they are unable to eliminate strong degeneracies among cloud parameters. Our investigation of a generic "warm Neptune" with photochemical haze parameterization also shows promising results in constraining atmospheric and haze properties in the cooler temperature regime.

Original languageEnglish (US)
Article number144
JournalAstrophysical Journal
Volume883
Issue number2
DOIs
StatePublished - Jan 1 2019
Externally publishedYes

Fingerprint

James Webb Space Telescope
extrasolar planets
haze
transit
parameterization
atmospheric composition
atmospheres
Neptune (planet)
Neptune
atmosphere
coolers
Jupiter (planet)
inference
Jupiter
signal-to-noise ratio
climate
metallicity
retrieval
signal to noise ratios
planet

Keywords

  • methods: Data analysis
  • planets and satellites: Atmospheres
  • techniques: Spectroscopic
  • telescopes

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this

Exploring Exoplanet Cloud Assumptions in JWST Transmission Spectra. / Mai, Chuhong; Line, Michael R.

In: Astrophysical Journal, Vol. 883, No. 2, 144, 01.01.2019.

Research output: Contribution to journalArticle

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