A high internal heat flux and large core in a warm Neptune exoplanet

• 成果类型: Article
• 署名作者: Welbanks, Luis; Bell, Taylor J.; Beatty, Thomas G.; Line, Michael R.; Ohno, Kazumasa; Fortney, Jonathan J.; Schlawin, Everett; Greene, Thomas P.; Rauscher, Emily; McGill, Peter; Murphy, Matthew; Parmentier, Vivien; Tang, Yao; Edelman, Isaac; Mukherjee, Sagnick; Wiser, Lindsey S.; Lagage, Pierre-Olivier; Dyrek, Achrene; Arnold, Kenneth E.
• 署名单位: Arizona State University; Arizona State University-Tempe; National Aeronautics & Space Administration (NASA); NASA Ames Research Center; University of Wisconsin System; University of Wisconsin Madison; University of California System; University of California Santa Cruz; National Institutes of Natural Sciences (NINS) - Japan; National Astronomical Observatory of Japan (NAOJ); University of Arizona; University of Michigan System; University of Michigan; United States Department of Energy (DOE); Lawrence Livermore National Laboratory; Universite Cote d'Azur; CEA; Centre National de la Recherche Scientifique (CNRS); Universite Paris Cite; Universite Paris Saclay
• 刊物名称: Nature
• ISSN/ISSBN: 0028-6733
• DOI: 10.1038/s41586-024-07514-w
• 发表日期: 2024-06-27
• 关键词: rotation-vibration spectrum; line lists; retrieval; atmosphere; RESOLUTION; methane; temperature; SCATTERING; efficient; planets

摘要

Interactions between exoplanetary atmospheres and internal properties have long been proposed to be drivers of the inflation mechanisms of gaseous planets and apparent atmospheric chemical disequilibrium conditions(1). However, transmission spectra of exoplanets have been limited in their ability to observationally confirm these theories owing to the limited wavelength coverage of the Hubble Space Telescope (HST) and inferences of single molecules, mostly H2O (ref. (2)). In this work, we present the panchromatic transmission spectrum of the approximately 750 K, low-density, Neptune-sized exoplanet WASP-107b using a combination of HST Wide Field Camera 3 (WFC3) and JWST Near-Infrared Camera (NIRCam) and Mid-Infrared Instrument (MIRI). From this spectrum, we detect spectroscopic features resulting from H2O (21 sigma), CH4 (5 sigma), CO (7 sigma), CO2 (29 sigma), SO2 (9 sigma) and NH3 (6 sigma). The presence of these molecules enables constraints on the atmospheric metal enrichment (M/H is 10-18x solar(3)), vertical mixing strength (log(10)K(zz) = 8.4-9.0 cm(2) s(-1)) and internal temperature (>345 K). The high internal temperature is suggestive of tidally driven inflation(4) acting on a Neptune-like internal structure, which can naturally explain the large radius and low density of the planet. These findings suggest that eccentricity-driven tidal heating is a critical process governing atmospheric chemistry and interior-structure inferences for most of the cool (<1,000 K) super-Earth-to-Saturn-mass exoplanet population.