The Radiative Effects of Photochemical Hazes on the Atmospheric Circulation and Phase Curves of Sub-Neptunes

The Radiative Effects of Photochemical Hazes on the Atmospheric Circulation and Phase Curves of Sub-Neptunes

Measuring the atmospheric composition of hazy sub-Neptunes like GJ 1214b through transmission spectroscopy is difficult because of the degeneracy between mean molecular weight (MMW) and haziness. It has been proposed that phase-curve observations can break this degeneracy because of the relationship...

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Main Authors: Maria E. Steinrueck, Vivien Parmentier, Laura Kreidberg, Peter Gao, Eliza M.-R. Kempton, Michael Zhang, Kevin B. Stevenson, Isaac Malsky, Michael T. Roman, Emily Rauscher, Matej Malik, Roxana Lupu, Tiffany Kataria, Anjali A. A. Piette, Jacob L. Bean, Matthew C. Nixon
Format: Article
Language:English
Published: IOP Publishing 2025-01-01
Series:The Astrophysical Journal
Subjects:
Exoplanet atmospheric dynamics
Exoplanet atmospheres
Exoplanet atmospheric structure
Extrasolar gaseous giant planets
Extrasolar gaseous planets
Online Access:https://doi.org/10.3847/1538-4357/adc99a
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Summary:Measuring the atmospheric composition of hazy sub-Neptunes like GJ 1214b through transmission spectroscopy is difficult because of the degeneracy between mean molecular weight (MMW) and haziness. It has been proposed that phase-curve observations can break this degeneracy because of the relationship between MMW and phase-curve amplitude. However, photochemical hazes can strongly affect phase-curve amplitudes as well. We present a large set of general circulation model simulations of the sub-Neptune GJ 1214b that include photochemical hazes with varying atmospheric composition, haze opacity, and haze optical properties. In our simulations, photochemical hazes cause temperature changes of up to 200 K, producing thermal inversions and cooling deeper regions. This results in increased phase-curve amplitudes and adds a considerable scatter to the phase-curve amplitude–metallicity relationship. However, we find that if the haze production rate is high enough to significantly alter the phase curve, the secondary eclipse spectrum will exhibit either emission features or strongly muted absorption features. Thus, the combination of a white-light phase curve and a secondary eclipse spectrum can successfully distinguish between a hazy, lower-MMW and a clear, high-MMW scenario.
ISSN:1538-4357

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