Signatures of Clouds in Hot Jupiter Atmospheres: Modeled High-resolution Emission Spectra from 3D General Circulation Models

• Published in: The Astrophysical journal Vol. 909; no. 1; p. 85
• Main Authors: Harada, Caleb K., Kempton, Eliza M.-R., Rauscher, Emily, Roman, Michael, Malsky, Isaac, Brinjikji, Marah, DiTomasso, Victoria
• Format: Journal Article
• Language: English
• Published: Philadelphia IOP Publishing 01.03.2021
• Subjects: Aerosols; Astrophysics; Atmosphere; Atmospheric circulation; Atmospheric models; Cloud formation; Clouds; Doppler effect; Emission spectra; Emissions; Extrasolar planets; Gas giant planets; General circulation models; Global winds; High resolution; Jupiter; Planetary atmospheres; Planetary orbits; Planetary rotation; Spectral emissivity; Temperature dependence; Thermal emission; Thickness; Three dimensional models
• ISSN: 0004-637X; 1538-4357
• DOI: 10.3847/1538-4357/abdc22

Abstract Observations of scattered light and thermal emission from hot Jupiter exoplanets have suggested the presence of inhomogeneous aerosols in their atmospheres. 3D general circulation models (GCMs) that attempt to model the effects of aerosols have been developed to understand the physical processes that underlie their dynamical structures. In this work, we investigate how different approaches to aerosol modeling in GCMs of hot Jupiters affect high-resolution thermal emission spectra throughout the duration of the planet’s orbit. Using results from a GCM with temperature-dependent cloud formation, we calculate spectra of a representative hot Jupiter with different assumptions regarding the vertical extent and thickness of clouds. We then compare these spectra to models in which clouds are absent or simply post-processed (i.e., added subsequently to the completed clear model). We show that the temperature-dependent treatment of clouds in the GCM produces high-resolution emission spectra that are markedly different from the clear and post-processed cases—both in the continuum flux levels and line profiles—and that increasing the vertical extent and thickness of clouds leads to bigger changes in these features. We evaluate the net Doppler shifts of the spectra induced by global winds and the planet’s rotation and show that they are strongly phase dependent, especially for models with thicker and more extended clouds. This work further demonstrates the importance of radiative feedback in cloudy atmospheric models of hot Jupiters, as this can have a significant impact on interpreting spectroscopic observations of exoplanet atmospheres.