Formation of planetary systems by pebble accretion and migration: How the radial pebble flux determines a terrestrial-planet or super-Earth growth mode
Autor(a) principal: | |
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Data de Publicação: | 2019 |
Outros Autores: | , , , , , |
Tipo de documento: | Artigo |
Idioma: | eng |
Título da fonte: | Repositório Institucional da UNESP |
Texto Completo: | http://dx.doi.org/10.1051/0004-6361/201834229 http://hdl.handle.net/11449/187890 |
Resumo: | Super-Earths - planets with sizes between the Earth and Neptune - are found in tighter orbits than that of the Earth around more than one third of main sequence stars. It has been proposed that super-Earths are scaled-up terrestrial planets that also formed similarly, through mutual accretion of planetary embryos, but in discs much denser than the solar protoplanetary disc. We argue instead that terrestrial planets and super-Earths have two clearly distinct formation pathways that are regulated by the pebble reservoir of the disc. Through numerical integrations, which combine pebble accretion and N-body gravity between embryos, we show that a difference of a factor of two in the pebble mass flux is enough to change the evolution from the terrestrial to the super-Earth growth mode. If the pebble mass flux is small, then the initial embryos within the ice line grow slowly and do not migrate substantially, resulting in a widely spaced population of approximately Mars-mass embryos when the gas disc dissipates. Subsequently, without gas being present, the embryos become unstable due to mutual gravitational interactions and a small number of terrestrial planets are formed by mutual collisions. The final terrestrial planets are at most five Earth masses. Instead, if the pebble mass flux is high, then the initial embryos within the ice line rapidly become sufficiently massive to migrate through the gas disc. Embryos concentrate at the inner edge of the disc and growth accelerates through mutual merging. This leads to the formation of a system of closely spaced super-Earths in the five to twenty Earth-mass range, bounded by the pebble isolation mass. Generally, instabilities of these super-Earth systems after the disappearance of the gas disc trigger additional merging events and dislodge the system from resonant chains. Therefore, the key difference between the two growth modes is whether embryos grow fast enough to undergo significant migration. The terrestrial growth mode produces small rocky planets on wider orbits like those in the solar system whereas the super-Earth growth mode produces planets in short-period orbits inside 1 AU, with masses larger than the Earth that should be surrounded by a primordial H/He atmosphere, unless subsequently lost by stellar irradiation. The pebble flux - which controls the transition between the two growth modes - may be regulated by the initial reservoir of solids in the disc or the presence of more distant giant planets that can halt the radial flow of pebbles. |
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Formation of planetary systems by pebble accretion and migration: How the radial pebble flux determines a terrestrial-planet or super-Earth growth modePlanets and satellites: compositionPlanets and satellites: dynamical evolution and stabilityPlanets and satellites: formationPlanets and satellites: terrestrial planetsProtoplanetary discsSuper-Earths - planets with sizes between the Earth and Neptune - are found in tighter orbits than that of the Earth around more than one third of main sequence stars. It has been proposed that super-Earths are scaled-up terrestrial planets that also formed similarly, through mutual accretion of planetary embryos, but in discs much denser than the solar protoplanetary disc. We argue instead that terrestrial planets and super-Earths have two clearly distinct formation pathways that are regulated by the pebble reservoir of the disc. Through numerical integrations, which combine pebble accretion and N-body gravity between embryos, we show that a difference of a factor of two in the pebble mass flux is enough to change the evolution from the terrestrial to the super-Earth growth mode. If the pebble mass flux is small, then the initial embryos within the ice line grow slowly and do not migrate substantially, resulting in a widely spaced population of approximately Mars-mass embryos when the gas disc dissipates. Subsequently, without gas being present, the embryos become unstable due to mutual gravitational interactions and a small number of terrestrial planets are formed by mutual collisions. The final terrestrial planets are at most five Earth masses. Instead, if the pebble mass flux is high, then the initial embryos within the ice line rapidly become sufficiently massive to migrate through the gas disc. Embryos concentrate at the inner edge of the disc and growth accelerates through mutual merging. This leads to the formation of a system of closely spaced super-Earths in the five to twenty Earth-mass range, bounded by the pebble isolation mass. Generally, instabilities of these super-Earth systems after the disappearance of the gas disc trigger additional merging events and dislodge the system from resonant chains. Therefore, the key difference between the two growth modes is whether embryos grow fast enough to undergo significant migration. The terrestrial growth mode produces small rocky planets on wider orbits like those in the solar system whereas the super-Earth growth mode produces planets in short-period orbits inside 1 AU, with masses larger than the Earth that should be surrounded by a primordial H/He atmosphere, unless subsequently lost by stellar irradiation. The pebble flux - which controls the transition between the two growth modes - may be regulated by the initial reservoir of solids in the disc or the presence of more distant giant planets that can halt the radial flow of pebbles.European Research CouncilDepartment of Astronomy and Theoretical Physics Lund Observatory Lund University, Box 43Laboratoire Lagrange UMR7293 CNRS Observatoire de la Côte d'Azur Université Côte d'Azur, Boulevard de l'ObservatoireDepartment of Earth and Planetary Sciences Technological Institute Northwestern University, F293/4, 2145 Sheridan RoadMax-Planck-Institut für Astronomie, Königstuhl 17UNESP Universidade Estadual Paulista Grupo de Dinàmica Orbital Planetologia, GuaratinguetàLaboratoire d'Astrophysique de Bordeaux CNRS and Université de Bordeaux, Allée Geoffroy St. HilaireUNESP Universidade Estadual Paulista Grupo de Dinàmica Orbital Planetologia, GuaratinguetàEuropean Research Council: 724687-PLANETESYSEuropean Research Council: 757448- PAMDORALund UniversityUniversité Côte d'AzurNorthwestern UniversityMax-Planck-Institut für AstronomieUniversidade Estadual Paulista (Unesp)CNRS and Université de BordeauxLambrechts, MichielMorbidelli, AlessandroJacobson, Seth A.Johansen, AndersBitsch, BertramIzidoro, Andre [UNESP]Raymond, Sean N.2019-10-06T15:50:29Z2019-10-06T15:50:29Z2019-07-01info:eu-repo/semantics/publishedVersioninfo:eu-repo/semantics/articlehttp://dx.doi.org/10.1051/0004-6361/201834229Astronomy and Astrophysics, v. 627.1432-07460004-6361http://hdl.handle.net/11449/18789010.1051/0004-6361/2018342292-s2.0-85069526206Scopusreponame:Repositório Institucional da UNESPinstname:Universidade Estadual Paulista (UNESP)instacron:UNESPengAstronomy and Astrophysicsinfo:eu-repo/semantics/openAccess2021-10-23T15:01:10Zoai:repositorio.unesp.br:11449/187890Repositório InstitucionalPUBhttp://repositorio.unesp.br/oai/requestopendoar:29462024-08-05T23:47:30.502263Repositório Institucional da UNESP - Universidade Estadual Paulista (UNESP)false |
dc.title.none.fl_str_mv |
Formation of planetary systems by pebble accretion and migration: How the radial pebble flux determines a terrestrial-planet or super-Earth growth mode |
title |
Formation of planetary systems by pebble accretion and migration: How the radial pebble flux determines a terrestrial-planet or super-Earth growth mode |
spellingShingle |
Formation of planetary systems by pebble accretion and migration: How the radial pebble flux determines a terrestrial-planet or super-Earth growth mode Lambrechts, Michiel Planets and satellites: composition Planets and satellites: dynamical evolution and stability Planets and satellites: formation Planets and satellites: terrestrial planets Protoplanetary discs |
title_short |
Formation of planetary systems by pebble accretion and migration: How the radial pebble flux determines a terrestrial-planet or super-Earth growth mode |
title_full |
Formation of planetary systems by pebble accretion and migration: How the radial pebble flux determines a terrestrial-planet or super-Earth growth mode |
title_fullStr |
Formation of planetary systems by pebble accretion and migration: How the radial pebble flux determines a terrestrial-planet or super-Earth growth mode |
title_full_unstemmed |
Formation of planetary systems by pebble accretion and migration: How the radial pebble flux determines a terrestrial-planet or super-Earth growth mode |
title_sort |
Formation of planetary systems by pebble accretion and migration: How the radial pebble flux determines a terrestrial-planet or super-Earth growth mode |
author |
Lambrechts, Michiel |
author_facet |
Lambrechts, Michiel Morbidelli, Alessandro Jacobson, Seth A. Johansen, Anders Bitsch, Bertram Izidoro, Andre [UNESP] Raymond, Sean N. |
author_role |
author |
author2 |
Morbidelli, Alessandro Jacobson, Seth A. Johansen, Anders Bitsch, Bertram Izidoro, Andre [UNESP] Raymond, Sean N. |
author2_role |
author author author author author author |
dc.contributor.none.fl_str_mv |
Lund University Université Côte d'Azur Northwestern University Max-Planck-Institut für Astronomie Universidade Estadual Paulista (Unesp) CNRS and Université de Bordeaux |
dc.contributor.author.fl_str_mv |
Lambrechts, Michiel Morbidelli, Alessandro Jacobson, Seth A. Johansen, Anders Bitsch, Bertram Izidoro, Andre [UNESP] Raymond, Sean N. |
dc.subject.por.fl_str_mv |
Planets and satellites: composition Planets and satellites: dynamical evolution and stability Planets and satellites: formation Planets and satellites: terrestrial planets Protoplanetary discs |
topic |
Planets and satellites: composition Planets and satellites: dynamical evolution and stability Planets and satellites: formation Planets and satellites: terrestrial planets Protoplanetary discs |
description |
Super-Earths - planets with sizes between the Earth and Neptune - are found in tighter orbits than that of the Earth around more than one third of main sequence stars. It has been proposed that super-Earths are scaled-up terrestrial planets that also formed similarly, through mutual accretion of planetary embryos, but in discs much denser than the solar protoplanetary disc. We argue instead that terrestrial planets and super-Earths have two clearly distinct formation pathways that are regulated by the pebble reservoir of the disc. Through numerical integrations, which combine pebble accretion and N-body gravity between embryos, we show that a difference of a factor of two in the pebble mass flux is enough to change the evolution from the terrestrial to the super-Earth growth mode. If the pebble mass flux is small, then the initial embryos within the ice line grow slowly and do not migrate substantially, resulting in a widely spaced population of approximately Mars-mass embryos when the gas disc dissipates. Subsequently, without gas being present, the embryos become unstable due to mutual gravitational interactions and a small number of terrestrial planets are formed by mutual collisions. The final terrestrial planets are at most five Earth masses. Instead, if the pebble mass flux is high, then the initial embryos within the ice line rapidly become sufficiently massive to migrate through the gas disc. Embryos concentrate at the inner edge of the disc and growth accelerates through mutual merging. This leads to the formation of a system of closely spaced super-Earths in the five to twenty Earth-mass range, bounded by the pebble isolation mass. Generally, instabilities of these super-Earth systems after the disappearance of the gas disc trigger additional merging events and dislodge the system from resonant chains. Therefore, the key difference between the two growth modes is whether embryos grow fast enough to undergo significant migration. The terrestrial growth mode produces small rocky planets on wider orbits like those in the solar system whereas the super-Earth growth mode produces planets in short-period orbits inside 1 AU, with masses larger than the Earth that should be surrounded by a primordial H/He atmosphere, unless subsequently lost by stellar irradiation. The pebble flux - which controls the transition between the two growth modes - may be regulated by the initial reservoir of solids in the disc or the presence of more distant giant planets that can halt the radial flow of pebbles. |
publishDate |
2019 |
dc.date.none.fl_str_mv |
2019-10-06T15:50:29Z 2019-10-06T15:50:29Z 2019-07-01 |
dc.type.status.fl_str_mv |
info:eu-repo/semantics/publishedVersion |
dc.type.driver.fl_str_mv |
info:eu-repo/semantics/article |
format |
article |
status_str |
publishedVersion |
dc.identifier.uri.fl_str_mv |
http://dx.doi.org/10.1051/0004-6361/201834229 Astronomy and Astrophysics, v. 627. 1432-0746 0004-6361 http://hdl.handle.net/11449/187890 10.1051/0004-6361/201834229 2-s2.0-85069526206 |
url |
http://dx.doi.org/10.1051/0004-6361/201834229 http://hdl.handle.net/11449/187890 |
identifier_str_mv |
Astronomy and Astrophysics, v. 627. 1432-0746 0004-6361 10.1051/0004-6361/201834229 2-s2.0-85069526206 |
dc.language.iso.fl_str_mv |
eng |
language |
eng |
dc.relation.none.fl_str_mv |
Astronomy and Astrophysics |
dc.rights.driver.fl_str_mv |
info:eu-repo/semantics/openAccess |
eu_rights_str_mv |
openAccess |
dc.source.none.fl_str_mv |
Scopus reponame:Repositório Institucional da UNESP instname:Universidade Estadual Paulista (UNESP) instacron:UNESP |
instname_str |
Universidade Estadual Paulista (UNESP) |
instacron_str |
UNESP |
institution |
UNESP |
reponame_str |
Repositório Institucional da UNESP |
collection |
Repositório Institucional da UNESP |
repository.name.fl_str_mv |
Repositório Institucional da UNESP - Universidade Estadual Paulista (UNESP) |
repository.mail.fl_str_mv |
|
_version_ |
1808129552596074496 |