Clouds and Hazes in GJ 1214 b’s Metal-rich Atmosphere

Journal article

The sub-Neptune GJ 1214 b has an infamously flat transmission spectrum, likely due to thick aerosols in its atmosphere. A recent JWST/MIRI spectroscopic phase curve of GJ 1214 b added to this picture, suggesting a highly reflective and metal-rich atmosphere. Using a 3D general circulation model with both photochemical hazes and condensate clouds, we characterize how different aerosol types affect the atmospheric structure of GJ 1214 b and manifest in its spectroscopic phase curve. Additionally, we reanalyze the original GJ 1214 b JWST phase curve. The reanalysis shows a hotter nightside, similar dayside temperature, and a lower, but still elevated, Bond albedo (0.42 ± 0.11) in comparison to the original results. We find that a scenario with both clouds and hazes is most consistent with the JWST phase curve. Reflective clouds or hazes are needed to explain the large Bond albedo, and hazes or a supersolar metallicity help account for the several hundred kelvin day–night temperature difference measured by the phase curve.

Authors: Malsky, I; Rauscher, E; Stevenson, K; Savel, AB; Steinrueck, ME

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: American Astronomical Society
• Journal: Astronomical Journal
• Volume: 169
• Issue: 4
• Article number: 221
• Publication date: 2025-03-21
• Acceptance date: 2025-02-17
• DOI: 10.3847/1538-3881/adb7e8
• EISSN: 1538-3881
• ISSN: 0004-6256
• Language: English
• Keywords: Exoplanet atmospheric composition; Exoplanet atmospheric dynamics; Exoplanet astronomy; Exoplanet atmospheres