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Fu G, Welbanks L, Deming D, Inglis J, Zhang M, Lothringer J, Ih J, Moses JI, Schlawin E, Knutson HA, Henry G, Greene T, Sing DK, Savel AB, Kempton EMR, Louie DR, Line M, Nixon M. Hydrogen sulfide and metal-enriched atmosphere for a Jupiter-mass exoplanet. Nature 2024; 632:752-756. [PMID: 38977019 DOI: 10.1038/s41586-024-07760-y] [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: 10/01/2023] [Accepted: 06/26/2024] [Indexed: 07/10/2024]
Abstract
As the closest transiting hot Jupiter to Earth, HD 189733b has been the benchmark planet for atmospheric characterization1-3. It has also been the anchor point for much of our theoretical understanding of exoplanet atmospheres from composition4, chemistry5,6, aerosols7 to atmospheric dynamics8, escape9 and modelling techniques10,11. Previous studies of HD 189733b have detected carbon and oxygen-bearing molecules H2O and CO (refs. 12,13) in the atmosphere. The presence of CO2 and CH4 has been claimed14,15 but later disputed12,16,17. The inferred metallicity based on these measurements, a key parameter in tracing planet formation locations18, varies from depletion19,20 to enhancement21,22, hindered by limited wavelength coverage and precision of the observations. Here we report detections of H2O (13.4σ), CO2 (11.2σ), CO (5σ) and H2S (4.5σ) in the transmission spectrum (2.4-5.0 μm) of HD 189733b. With an equilibrium temperature of about 1,200 K, H2O, CO and H2S are the main reservoirs for oxygen, carbon and sulfur. Based on the measured abundances of these three main volatile elements, we infer an atmospheric metallicity of three to five times stellar. The upper limit on the methane abundance at 5σ is 0.1 ppm, which indicates a low carbon-to-oxygen ratio (<0.2), suggesting formation through the accretion of water-rich icy planetesimals. The low oxygen-to-sulfur and carbon-to-sulfur ratios also support the planetesimal accretion formation pathway23.
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Affiliation(s)
- Guangwei Fu
- Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD, USA.
| | - Luis Welbanks
- School of Earth and Space Exploration, Arizona State University, Tempe, AZ, USA
| | - Drake Deming
- Department of Astronomy, University of Maryland, College Park, MD, USA
| | - Julie Inglis
- Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA, USA
| | - Michael Zhang
- Department of Astronomy and Astrophysics, University of Chicago, Chicago, IL, USA
| | | | - Jegug Ih
- Department of Astronomy, University of Maryland, College Park, MD, USA
| | | | | | - Heather A Knutson
- Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA, USA
| | - Gregory Henry
- Center of Excellence in Information Systems, Tennessee State University, Nashville, TN, USA
| | | | - David K Sing
- Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD, USA
| | - Arjun B Savel
- Department of Astronomy, University of Maryland, College Park, MD, USA
| | - Eliza M-R Kempton
- Department of Astronomy, University of Maryland, College Park, MD, USA
| | - Dana R Louie
- NASA Goddard Space Flight Center, Greenbelt, MD, USA
| | - Michael Line
- School of Earth and Space Exploration, Arizona State University, Tempe, AZ, USA
| | - Matt Nixon
- Department of Astronomy, University of Maryland, College Park, MD, USA
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Kim D, Smith RF, Ocampo IK, Coppari F, Marshall MC, Ginnane MK, Wicks JK, Tracy SJ, Millot M, Lazicki A, Rygg JR, Eggert JH, Duffy TS. Structure and density of silicon carbide to 1.5 TPa and implications for extrasolar planets. Nat Commun 2022; 13:2260. [PMID: 35477934 PMCID: PMC9046200 DOI: 10.1038/s41467-022-29762-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2021] [Accepted: 03/16/2022] [Indexed: 11/10/2022] Open
Abstract
There has been considerable recent interest in the high-pressure behavior of silicon carbide, a potential major constituent of carbon-rich exoplanets. In this work, the atomic-level structure of SiC was determined through in situ X-ray diffraction under laser-driven ramp compression up to 1.5 TPa; stresses more than seven times greater than previous static and shock data. Here we show that the B1-type structure persists over this stress range and we have constrained its equation of state (EOS). Using this data we have determined the first experimentally based mass-radius curves for a hypothetical pure SiC planet. Interior structure models are constructed for planets consisting of a SiC-rich mantle and iron-rich core. Carbide planets are found to be ~10% less dense than corresponding terrestrial planets.
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Affiliation(s)
- D Kim
- Department of Geosciences, Princeton University, Princeton, NJ, USA.
| | - R F Smith
- Lawrence Livermore National Laboratory, Livermore, CA, USA
| | - I K Ocampo
- Department of Geosciences, Princeton University, Princeton, NJ, USA
| | - F Coppari
- Lawrence Livermore National Laboratory, Livermore, CA, USA
| | - M C Marshall
- Laboratory for Laser Energetics, University of Rochester, Rochester, NY, USA
| | - M K Ginnane
- Laboratory for Laser Energetics, University of Rochester, Rochester, NY, USA
| | - J K Wicks
- Department of Earth & Planetary Sciences, Johns Hopkins University, Baltimore, MD, USA
| | - S J Tracy
- Earth and Planets Laboratory, Carnegie Institution for Science, Washington, DC, USA
| | - M Millot
- Lawrence Livermore National Laboratory, Livermore, CA, USA
| | - A Lazicki
- Lawrence Livermore National Laboratory, Livermore, CA, USA
| | - J R Rygg
- Laboratory for Laser Energetics, University of Rochester, Rochester, NY, USA
| | - J H Eggert
- Lawrence Livermore National Laboratory, Livermore, CA, USA
| | - T S Duffy
- Department of Geosciences, Princeton University, Princeton, NJ, USA
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Zeng L, Jacobsen SB, Sasselov DD, Petaev MI, Vanderburg A, Lopez-Morales M, Perez-Mercader J, Mattsson TR, Li G, Heising MZ, Bonomo AS, Damasso M, Berger TA, Cao H, Levi A, Wordsworth RD. Growth model interpretation of planet size distribution. Proc Natl Acad Sci U S A 2019; 116:9723-9728. [PMID: 31036661 PMCID: PMC6525489 DOI: 10.1073/pnas.1812905116] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The radii and orbital periods of 4,000+ confirmed/candidate exoplanets have been precisely measured by the Kepler mission. The radii show a bimodal distribution, with two peaks corresponding to smaller planets (likely rocky) and larger intermediate-size planets, respectively. While only the masses of the planets orbiting the brightest stars can be determined by ground-based spectroscopic observations, these observations allow calculation of their average densities placing constraints on the bulk compositions and internal structures. However, an important question about the composition of planets ranging from 2 to 4 Earth radii (R⊕) still remains. They may either have a rocky core enveloped in a H2-He gaseous envelope (gas dwarfs) or contain a significant amount of multicomponent, H2O-dominated ices/fluids (water worlds). Planets in the mass range of 10-15 M⊕, if half-ice and half-rock by mass, have radii of 2.5 R⊕, which exactly match the second peak of the exoplanet radius bimodal distribution. Any planet in the 2- to 4-R⊕ range requires a gas envelope of at most a few mass percentage points, regardless of the core composition. To resolve the ambiguity of internal compositions, we use a growth model and conduct Monte Carlo simulations to demonstrate that many intermediate-size planets are "water worlds."
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Affiliation(s)
- Li Zeng
- Department of Earth and Planetary Sciences, Harvard University, Cambridge, MA 02138;
- Center for Astrophysics | Harvard & Smithsonian, Department of Astronomy, Harvard University, MA 02138
| | - Stein B Jacobsen
- Department of Earth and Planetary Sciences, Harvard University, Cambridge, MA 02138
| | - Dimitar D Sasselov
- Center for Astrophysics | Harvard & Smithsonian, Department of Astronomy, Harvard University, MA 02138
| | - Michail I Petaev
- Department of Earth and Planetary Sciences, Harvard University, Cambridge, MA 02138
- Center for Astrophysics | Harvard & Smithsonian, Department of Astronomy, Harvard University, MA 02138
| | - Andrew Vanderburg
- Department of Astronomy, The University of Texas at Austin, Austin, TX 78712
| | - Mercedes Lopez-Morales
- Center for Astrophysics | Harvard & Smithsonian, Department of Astronomy, Harvard University, MA 02138
| | - Juan Perez-Mercader
- Department of Earth and Planetary Sciences, Harvard University, Cambridge, MA 02138
| | - Thomas R Mattsson
- High Energy Density Physics Theory Department, Sandia National Laboratories, Albuquerque, NM 87185
| | - Gongjie Li
- School of Physics, Georgia Institute of Technology, Atlanta, GA 30313
| | - Matthew Z Heising
- Center for Astrophysics | Harvard & Smithsonian, Department of Astronomy, Harvard University, MA 02138
| | - Aldo S Bonomo
- Istituto Nazionale di Astrofisica-Osservatorio Astrofisico di Torino, 10025 Pino Torinese, Italy
| | - Mario Damasso
- Istituto Nazionale di Astrofisica-Osservatorio Astrofisico di Torino, 10025 Pino Torinese, Italy
| | - Travis A Berger
- Institute for Astronomy, University of Hawaii, Honolulu, HI 96822
| | - Hao Cao
- Department of Earth and Planetary Sciences, Harvard University, Cambridge, MA 02138
| | - Amit Levi
- Center for Astrophysics | Harvard & Smithsonian, Department of Astronomy, Harvard University, MA 02138
| | - Robin D Wordsworth
- Department of Earth and Planetary Sciences, Harvard University, Cambridge, MA 02138
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