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Welbanks L, Bell TJ, Beatty TG, Line MR, Ohno K, Fortney JJ, Schlawin E, Greene TP, Rauscher E, McGill P, Murphy M, Parmentier V, Tang Y, Edelman I, Mukherjee S, Wiser LS, Lagage PO, Dyrek A, Arnold KE. A high internal heat flux and large core in a warm Neptune exoplanet. Nature 2024; 630:836-840. [PMID: 38768634 DOI: 10.1038/s41586-024-07514-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2024] [Accepted: 05/02/2024] [Indexed: 05/22/2024]
Abstract
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 conditions1. 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 (21σ), CH4 (5σ), CO (7σ), CO2 (29σ), SO2 (9σ) and NH3 (6σ). The presence of these molecules enables constraints on the atmospheric metal enrichment (M/H is 10-18× solar3), vertical mixing strength (log10Kzz = 8.4-9.0 cm2 s-1) and internal temperature (>345 K). The high internal temperature is suggestive of tidally driven inflation4 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.
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Affiliation(s)
- Luis Welbanks
- School of Earth and Space Exploration, Arizona State University, Tempe, AZ, USA.
| | - Taylor J Bell
- Bay Area Environmental Research Institute, NASA's Ames Research Center, Moffett Field, CA, USA
- Space Science and Astrobiology Division, NASA's Ames Research Center, Moffett Field, CA, USA
| | - Thomas G Beatty
- Department of Astronomy, University of Wisconsin-Madison, Madison, WI, USA
| | - Michael R Line
- School of Earth and Space Exploration, Arizona State University, Tempe, AZ, USA
| | - Kazumasa Ohno
- Department of Astronomy and Astrophysics, University of California, Santa Cruz, Santa Cruz, CA, USA
- Division of Science, National Astronomical Observatory of Japan (NAOJ), Tokyo, Japan
| | - Jonathan J Fortney
- Department of Astronomy and Astrophysics, University of California, Santa Cruz, Santa Cruz, CA, USA
| | | | - Thomas P Greene
- Space Science and Astrobiology Division, NASA's Ames Research Center, Moffett Field, CA, USA
| | - Emily Rauscher
- Department of Astronomy, University of Michigan, Ann Arbor, MI, USA
| | - Peter McGill
- Space Science Institute, Lawrence Livermore National Laboratory, Livermore, CA, USA
| | - Matthew Murphy
- Steward Observatory, University of Arizona, Tucson, AZ, USA
| | - Vivien Parmentier
- Laboratoire Lagrange, Observatoire de la Côte d'Azur, Université Côte d'Azur, Nice, France
| | - Yao Tang
- Department of Astronomy and Astrophysics, University of California, Santa Cruz, Santa Cruz, CA, USA
| | - Isaac Edelman
- Bay Area Environmental Research Institute, NASA's Ames Research Center, Moffett Field, CA, USA
| | - Sagnick Mukherjee
- Department of Astronomy and Astrophysics, University of California, Santa Cruz, Santa Cruz, CA, USA
| | - Lindsey S Wiser
- School of Earth and Space Exploration, Arizona State University, Tempe, AZ, USA
| | - Pierre-Olivier Lagage
- Université Paris-Saclay, Université Paris Cité, CEA, CNRS, AIM, Gif-sur-Yvette, France
| | - Achrène Dyrek
- Université Paris-Saclay, Université Paris Cité, CEA, CNRS, AIM, Gif-sur-Yvette, France
| | - Kenneth E Arnold
- Department of Astronomy, University of Wisconsin-Madison, Madison, WI, USA
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