Aerosol Constraints on the Atmosphere of the Hot Saturn-mass planet WASP-49b

Abstract

The strong, nearly wavelength-independent absorption cross section of aerosols produces featureless exoplanet transmission spectra, limiting our ability to characterize their atmospheres. Here we show that even in the presence of featureless spectra, we can still characterize certain atmospheric properties. Specifically, we constrain the upper and lower pressure boundaries of aerosol layers, and present plausible composition candidates. We study the case of the bloated Saturn-mass planet WASP-49b, where near-infrared observations reveal a flat transmission spectrum between 0.7 and 1.0 {\microns}. First, we use a hydrodynamic upper-atmosphere code to estimate the pressure reached by the ionizing stellar high-energy photons at $10^{-8}$ bar, setting the upper pressure boundary where aerosols could exist. Then, we combine HELIOS and Pyrat Bay radiative-transfer models to constrain the temperature and photospheric pressure of atmospheric aerosols, in a Bayesian framework. For WASP-49b, we constrain the transmission photosphere (hence, the aerosol deck boundaries) to pressures above $10^{-5}$ bar (100$\times$ solar metallicity), $10^{-4}$ bar (solar), and $10^{-3}$ bar (0.1$\times$ solar) as lower boundary, and below $10^{-7}$ bar as upper boundary. Lastly, we compare condensation curves of aerosol compounds with the planet's pressure-temperature profile to identify plausible condensates responsible for the absorption. Under these circumstances, we find as candidates: Na${}_2$S (at 100$\times$ solar metallicity); Cr and MnS (at solar and 0.1$\times$ solar); and forsterite, enstatite, and alabandite (at 0.1$\times$ solar).

arXiv commentAccepted for publication in ApJ

References in corpus (34)

• The NumPy array: a structure for efficient numerical computation
• A continuum from clear to cloudy hot-Jupiter exoplanets without primordial water depletion
• Clouds in the atmosphere of the super-Earth exoplanet GJ 1214b
• The stellar activity-rotation relationship and the evolution of stellar dynamos
• A Unified Theory for the Atmospheres of the Hot and Very Hot Jupiters: Two Classes of Irradiated Atmospheres
• Detection of atmospheric haze on an extrasolar planet: The 0.55 - 1.05 micron transmission spectrum of HD189733b with the Hubble Space Telescope
• A Possible Bifurcation in Atmospheres of Strongly Irradiated Stars and Planets
• Neglected Clouds in T and Y Dwarf Atmospheres
• A Precise Water Abundance Measurement for the Hot Jupiter WASP-43b
• Rayleigh scattering in the transit spectrum of HD 189733b
• Estimation of the XUV radiation onto close planets and their evaporation
• A featureless transmission spectrum for the Neptune-mass exoplanet GJ 436b
• Can TiO Explain Thermal Inversions in the Upper Atmospheres of Irradiated Giant Planets?
• Transitions in the cloud composition of hot Jupiters
• Atmospheric Chemistry in Giant Planets, Brown Dwarfs, and Low-Mass Dwarf Stars II. Sulfur and Phosphorus
• Atmospheric Chemistry in Giant Planets, Brown Dwarfs, and Low-Mass Dwarf Stars III. Iron, Magnesium, and Silicon
• Thermal Emission and Albedo Spectra of Super Earths with Flat Transmission Spectra
• The Near-Infrared and Optical Spectra of Methane Dwarfs and Brown Dwarfs
• The escape of heavy atoms from the ionosphere of HD209458b. I. A photochemical-dynamical model of the thermosphere
• ExoMol molecular line lists - XVI: The rotation-vibration spectrum of hot H${}_2$S
• Transmission spectral properties of clouds for hot Jupiter exoplanets
• A consistent retrieval analysis of 10 Hot Jupiters observed in transmission
• HELIOS: An Open-source, GPU-accelerated Radiative Transfer Code For Self-consistent Exoplanetary Atmospheres
• Spatially resolved eastward winds and rotation of HD 189733b
• Exoplanet Transit Spectroscopy Using WFC3: WASP-12 b, WASP-17 b, and WASP-19 b
• Quantifying and Predicting the Presence of Clouds in Exoplanet Atmospheres
• On Correlated-noise Analyses Applied To Exoplanet Light Curves
• WASP-42 b and WASP-49 b: two new transiting sub-Jupiters
• Hot Exoplanet Atmospheres Resolved with Transit Spectroscopy (HEARTS) I. Detection of hot neutral sodium at high altitudes on WASP-49b
• A Cloudiness Index for Transiting Exoplanets Based on the Sodium and Potassium Lines: Tentative Evidence for Hotter Atmospheres Being Less Cloudy at Visible Wavelengths
• TEA: A Code for Calculating Thermochemical Equilibrium Abundances
• Thermal mass loss of protoplanetary cores with hydrogen-dominated atmospheres: The influences of ionization and orbital distance
• FORS2 observes a multi-epoch transmission spectrum of the hot Saturn-mass exoplanet WASP-49b
• A Non-isothermal Theory for Interpreting Sodium Lines in Transmission Spectra of Exoplanets

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