Refining the Transit-timing and Photometric Analysis of TRAPPIST-1: Masses, Radii, Densities, Dynamics, and Ephemerides
We have collected transit times for the TRAPPIST-1 system with the Spitzer Space Telescope over four years. We add to these ground-based, HST, and K2 transit-time measurements, and revisit an N -body dynamical analysis of the seven-planet system using our complete set of times from which we refine t...
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IOP Publishing
2021-01-01
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| Series: | The Planetary Science Journal |
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| Online Access: | https://doi.org/10.3847/PSJ/abd022 |
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| author | Eric Agol Caroline Dorn Simon L. Grimm Martin Turbet Elsa Ducrot Laetitia Delrez Michaël Gillon Brice-Olivier Demory Artem Burdanov Khalid Barkaoui Zouhair Benkhaldoun Emeline Bolmont Adam Burgasser Sean Carey Julien de Wit Daniel Fabrycky Daniel Foreman-Mackey Jonas Haldemann David M. Hernandez James Ingalls Emmanuel Jehin Zachary Langford Jérémy Leconte Susan M. Lederer Rodrigo Luger Renu Malhotra Victoria S. Meadows Brett M. Morris Francisco J. Pozuelos Didier Queloz Sean N. Raymond Franck Selsis Marko Sestovic Amaury H. M. J. Triaud Valerie Van Grootel |
| author_facet | Eric Agol Caroline Dorn Simon L. Grimm Martin Turbet Elsa Ducrot Laetitia Delrez Michaël Gillon Brice-Olivier Demory Artem Burdanov Khalid Barkaoui Zouhair Benkhaldoun Emeline Bolmont Adam Burgasser Sean Carey Julien de Wit Daniel Fabrycky Daniel Foreman-Mackey Jonas Haldemann David M. Hernandez James Ingalls Emmanuel Jehin Zachary Langford Jérémy Leconte Susan M. Lederer Rodrigo Luger Renu Malhotra Victoria S. Meadows Brett M. Morris Francisco J. Pozuelos Didier Queloz Sean N. Raymond Franck Selsis Marko Sestovic Amaury H. M. J. Triaud Valerie Van Grootel |
| author_sort | Eric Agol |
| collection | DOAJ |
| description | We have collected transit times for the TRAPPIST-1 system with the Spitzer Space Telescope over four years. We add to these ground-based, HST, and K2 transit-time measurements, and revisit an N -body dynamical analysis of the seven-planet system using our complete set of times from which we refine the mass ratios of the planets to the star. We next carry out a photodynamical analysis of the Spitzer light curves to derive the density of the host star and the planet densities. We find that all seven planets’ densities may be described with a single rocky mass–radius relation which is depleted in iron relative to Earth, with Fe 21 wt% versus 32 wt% for Earth, and otherwise Earth-like in composition. Alternatively, the planets may have an Earth-like composition but enhanced in light elements, such as a surface water layer or a core-free structure with oxidized iron in the mantle. We measure planet masses to a precision of 3%–5%, equivalent to a radial-velocity (RV) precision of 2.5 cm s ^−1 , or two orders of magnitude more precise than current RV capabilities. We find the eccentricities of the planets are very small, the orbits are extremely coplanar, and the system is stable on 10 Myr timescales. We find evidence of infrequent timing outliers, which we cannot explain with an eighth planet; we instead account for the outliers using a robust likelihood function. We forecast JWST timing observations and speculate on possible implications of the planet densities for the formation, migration, and evolution of the planet system. |
| first_indexed | 2024-03-08T15:58:13Z |
| format | Article |
| id | doaj.art-1851cb4eb5c443c383b21039f9ea104a |
| institution | Directory Open Access Journal |
| issn | 2632-3338 |
| language | English |
| last_indexed | 2024-03-08T15:58:13Z |
| publishDate | 2021-01-01 |
| publisher | IOP Publishing |
| record_format | Article |
| series | The Planetary Science Journal |
| spelling | doaj.art-1851cb4eb5c443c383b21039f9ea104a2024-01-08T14:12:17ZengIOP PublishingThe Planetary Science Journal2632-33382021-01-0121110.3847/PSJ/abd022Refining the Transit-timing and Photometric Analysis of TRAPPIST-1: Masses, Radii, Densities, Dynamics, and EphemeridesEric Agol0https://orcid.org/0000-0002-0802-9145Caroline Dorn1https://orcid.org/0000-0001-6110-4610Simon L. Grimm2https://orcid.org/0000-0002-0632-4407Martin Turbet3https://orcid.org/0000-0003-2260-9856Elsa Ducrot4https://orcid.org/0000-0002-7008-6888Laetitia Delrez5https://orcid.org/0000-0001-6108-4808Michaël Gillon6https://orcid.org/0000-0003-1462-7739Brice-Olivier Demory7https://orcid.org/0000-0002-9355-5165Artem Burdanov8https://orcid.org/0000-0001-9892-2406Khalid Barkaoui9https://orcid.org/0000-0003-1464-9276Zouhair Benkhaldoun10https://orcid.org/0000-0001-6285-9847Emeline Bolmont11https://orcid.org/0000-0001-5657-4503Adam Burgasser12https://orcid.org/0000-0002-6523-9536Sean Carey13https://orcid.org/0000-0002-0221-6871Julien de Wit14https://orcid.org/0000-0003-2415-2191Daniel Fabrycky15https://orcid.org/0000-0003-3750-0183Daniel Foreman-Mackey16https://orcid.org/0000-0002-9328-5652Jonas Haldemann17https://orcid.org/0000-0003-1231-2389David M. Hernandez18https://orcid.org/0000-0001-7648-0926James Ingalls19https://orcid.org/0000-0003-4714-1364Emmanuel Jehin20https://orcid.org/0000-0001-8923-488XZachary Langford21https://orcid.org/0000-0001-7574-4440Jérémy Leconte22https://orcid.org/0000-0002-3555-480XSusan M. Lederer23https://orcid.org/0000-0003-2805-8653Rodrigo Luger24https://orcid.org/0000-0002-0296-3826Renu Malhotra25https://orcid.org/0000-0002-1226-3305Victoria S. Meadows26https://orcid.org/0000-0002-1386-1710Brett M. Morris27https://orcid.org/0000-0003-2528-3409Francisco J. Pozuelos28https://orcid.org/0000-0003-1572-7707Didier Queloz29https://orcid.org/0000-0002-3012-0316Sean N. Raymond30https://orcid.org/0000-0001-8974-0758Franck Selsis31https://orcid.org/0000-0001-9619-5356Marko Sestovic32https://orcid.org/0000-0002-8124-8360Amaury H. M. J. Triaud33https://orcid.org/0000-0002-5510-8751Valerie Van Grootel34https://orcid.org/0000-0003-2144-4316Astronomy Department and Virtual Planetary Laboratory, University of Washington , Seattle, WA 98195, USA ; agol@uw.eduUniversity of Zurich, Institute of Computational Sciences , Winterthurerstrasse 190, CH-8057, Zurich, SwitzerlandCenter for Space and Habitability, University of Bern , Gesellschaftsstrasse 6, CH-3012, Bern, SwitzerlandObservatoire de Genève, Université de Genève , 51 Chemin des Maillettes, CH-1290 Sauverny, SwitzerlandAstrobiology Research Unit, Université de Liège , Allée du 6 Août 19C, B-4000 Liège, BelgiumObservatoire de Genève, Université de Genève , 51 Chemin des Maillettes, CH-1290 Sauverny, Switzerland; Astrobiology Research Unit, Université de Liège , Allée du 6 Août 19C, B-4000 Liège, Belgium; Space Sciences, Technologies and Astrophysics Research (STAR) Institute, Université de Liège , Allée du 6 Août 19C, B-4000 Liège, BelgiumAstrobiology Research Unit, Université de Liège , Allée du 6 Août 19C, B-4000 Liège, BelgiumCenter for Space and Habitability, University of Bern , Gesellschaftsstrasse 6, CH-3012, Bern, SwitzerlandDepartment of Earth, Atmospheric and Planetary Science, Massachusetts Institute of Technology , 77 Massachusetts Avenue, Cambridge, MA 02139, USAAstrobiology Research Unit, Université de Liège , Allée du 6 Août 19C, B-4000 Liège, Belgium; Oukaimeden Observatory, High Energy Physics and Astrophysics Laboratory, Cadi Ayyad University , Marrakech, MoroccoOukaimeden Observatory, High Energy Physics and Astrophysics Laboratory, Cadi Ayyad University , Marrakech, MoroccoObservatoire de Genève, Université de Genève , 51 Chemin des Maillettes, CH-1290 Sauverny, SwitzerlandCenter for Astrophysics and Space Science, University of California San Diego , La Jolla, CA 92093, USAIPAC, California Institute of Technology , 1200 E California Boulevard, Mail Code 314-6, Pasadena, CA 91125, USADepartment of Earth, Atmospheric and Planetary Science, Massachusetts Institute of Technology , 77 Massachusetts Avenue, Cambridge, MA 02139, USADepartment of Astronomy & Astrophysics, University of Chicago , 5640 S. Ellis Avenue, Chicago, IL 60637, USACenter for Computational Astrophysics, Flatiron Institute , Simons Foundation, 162 5th Avenue, New York, NY 10010, USAUniversity of Bern , Gesellschaftsstrasse 6, CH-3012, Bern, SwitzerlandHarvard-Smithsonian Center for Astrophysics , 60 Garden Street, MS 51, Cambridge, MA 02138, USAIPAC, California Institute of Technology , 1200 E California Boulevard, Mail Code 314-6, Pasadena, CA 91125, USASpace Sciences, Technologies and Astrophysics Research (STAR) Institute, Université de Liège , Allée du 6 Août 19C, B-4000 Liège, BelgiumAstronomy Department and Virtual Planetary Laboratory, University of Washington , Seattle, WA 98195, USA ; agol@uw.eduLaboratoire d’astrophysique de Bordeaux, Univ. Bordeaux , CNRS, B18N, Allée Geoffroy Saint-Hilaire, F-33615 Pessac, FranceNASA Johnson Space Center , 2101 NASA Parkway, Houston TX 77058, USACenter for Computational Astrophysics, Flatiron Institute , Simons Foundation, 162 5th Avenue, New York, NY 10010, USALunar and Planetary Laboratory, The University of Arizona , Tucson, AZ 85721, USAAstronomy Department and Virtual Planetary Laboratory, University of Washington , Seattle, WA 98195, USA ; agol@uw.eduCenter for Space and Habitability, University of Bern , Gesellschaftsstrasse 6, CH-3012, Bern, SwitzerlandAstrobiology Research Unit, Université de Liège , Allée du 6 Août 19C, B-4000 Liège, Belgium; Space Sciences, Technologies and Astrophysics Research (STAR) Institute, Université de Liège , Allée du 6 Août 19C, B-4000 Liège, BelgiumCavendish Laboratory , JJ Thomson Avenue, Cambridge, CB3 0H3, UKLaboratoire d’astrophysique de Bordeaux, Univ. Bordeaux , CNRS, B18N, Allée Geoffroy Saint-Hilaire, F-33615 Pessac, FranceLaboratoire d’astrophysique de Bordeaux, Univ. Bordeaux , CNRS, B18N, Allée Geoffroy Saint-Hilaire, F-33615 Pessac, FranceCenter for Space and Habitability, University of Bern , Gesellschaftsstrasse 6, CH-3012, Bern, SwitzerlandSchool of Physics & Astronomy, University of Birmingham , Edgbaston, Birmimgham B15 2TT, UKSpace Sciences, Technologies and Astrophysics Research (STAR) Institute, Université de Liège , Allée du 6 Août 19C, B-4000 Liège, BelgiumWe have collected transit times for the TRAPPIST-1 system with the Spitzer Space Telescope over four years. We add to these ground-based, HST, and K2 transit-time measurements, and revisit an N -body dynamical analysis of the seven-planet system using our complete set of times from which we refine the mass ratios of the planets to the star. We next carry out a photodynamical analysis of the Spitzer light curves to derive the density of the host star and the planet densities. We find that all seven planets’ densities may be described with a single rocky mass–radius relation which is depleted in iron relative to Earth, with Fe 21 wt% versus 32 wt% for Earth, and otherwise Earth-like in composition. Alternatively, the planets may have an Earth-like composition but enhanced in light elements, such as a surface water layer or a core-free structure with oxidized iron in the mantle. We measure planet masses to a precision of 3%–5%, equivalent to a radial-velocity (RV) precision of 2.5 cm s ^−1 , or two orders of magnitude more precise than current RV capabilities. We find the eccentricities of the planets are very small, the orbits are extremely coplanar, and the system is stable on 10 Myr timescales. We find evidence of infrequent timing outliers, which we cannot explain with an eighth planet; we instead account for the outliers using a robust likelihood function. We forecast JWST timing observations and speculate on possible implications of the planet densities for the formation, migration, and evolution of the planet system.https://doi.org/10.3847/PSJ/abd022Extrasolar rocky planetsExoplanet dynamicsInfrared photometryHabitable planetsTransit timing variation methodTransit photometry |
| spellingShingle | Eric Agol Caroline Dorn Simon L. Grimm Martin Turbet Elsa Ducrot Laetitia Delrez Michaël Gillon Brice-Olivier Demory Artem Burdanov Khalid Barkaoui Zouhair Benkhaldoun Emeline Bolmont Adam Burgasser Sean Carey Julien de Wit Daniel Fabrycky Daniel Foreman-Mackey Jonas Haldemann David M. Hernandez James Ingalls Emmanuel Jehin Zachary Langford Jérémy Leconte Susan M. Lederer Rodrigo Luger Renu Malhotra Victoria S. Meadows Brett M. Morris Francisco J. Pozuelos Didier Queloz Sean N. Raymond Franck Selsis Marko Sestovic Amaury H. M. J. Triaud Valerie Van Grootel Refining the Transit-timing and Photometric Analysis of TRAPPIST-1: Masses, Radii, Densities, Dynamics, and Ephemerides The Planetary Science Journal Extrasolar rocky planets Exoplanet dynamics Infrared photometry Habitable planets Transit timing variation method Transit photometry |
| title | Refining the Transit-timing and Photometric Analysis of TRAPPIST-1: Masses, Radii, Densities, Dynamics, and Ephemerides |
| title_full | Refining the Transit-timing and Photometric Analysis of TRAPPIST-1: Masses, Radii, Densities, Dynamics, and Ephemerides |
| title_fullStr | Refining the Transit-timing and Photometric Analysis of TRAPPIST-1: Masses, Radii, Densities, Dynamics, and Ephemerides |
| title_full_unstemmed | Refining the Transit-timing and Photometric Analysis of TRAPPIST-1: Masses, Radii, Densities, Dynamics, and Ephemerides |
| title_short | Refining the Transit-timing and Photometric Analysis of TRAPPIST-1: Masses, Radii, Densities, Dynamics, and Ephemerides |
| title_sort | refining the transit timing and photometric analysis of trappist 1 masses radii densities dynamics and ephemerides |
| topic | Extrasolar rocky planets Exoplanet dynamics Infrared photometry Habitable planets Transit timing variation method Transit photometry |
| url | https://doi.org/10.3847/PSJ/abd022 |
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