Last giant impact on Uranus: constraints on oligarchic masses in the trans-Saturnian region

Autores
Parisi, Mirta Gabriela
Año de publicación
2011
Idioma
inglés
Tipo de recurso
artículo
Estado
versión publicada
Descripción
Context. Modern models of the formation of ice giants attempt to account for the formation of Uranus and Neptune within the protoplanetary disk lifetime. These models assume a higher initial surface density well above that of the minimum mass solar nebula model and/or the formation of all giant planets in an inner compact configuration. Other effects include planetesimals migration due to gas drag and the small size of the accreted planetesimals, which accelerates the accretion rate. However, at present, none of these models account for the spin properties of the ice giants. Aims. Stochastic impacts by large bodies are, at present, the usually accepted mechanisms able to account for the obliquity of the ice giants. We attempt to set constraints on giant impacts as the cause of Uranus’s current obliquity of 98° and on the impactor masses. Methods. Since stochastic collisions among embryos are assumed to occur beyond oligarchy, we model the angular momentum transfer to proto-Uranus by the last stochastic collision (GC) between the protoplanet and an oligarchic mass at the end of Uranus’s formation. We take a minimum impactor mass mi of 1 m. Results. We find that an oligarchic mass mi ~ 1 m⊕ ≤ mi ≤ 4.5 m would be required at the GC to reproduce the present rotational properties of Uranus. An impact with mi > 4.5 m is not possible, unless the impact parameter of the collision is very small and/or the angle between the spin axis of Uranus prior and after the GC is higher than 130°. This result is valid if Uranus formed in situ or between 10 − 20 AU and does not depend on the occurrence of the GC after or during the possible migration of the planet. This result is very similar to one obtained for Neptune from its rotational properties. Conclusions. If the stage of stochastic impacts among oligarchs has occurred and if the present rotational status of Uranus is the result of such processes, the 4.5 m mass limit must be understood as an upper constraint on the oligarchic masses in the trans-Saturnian region at the end of ice giants’ formation. This result may be used to set constraints on planetary formation scenarios.
Instituto Argentino de Radioastronomía
Materia
Ciencias Astronómicas
Planets and satellites: general
Planets and satellites: formation
Nivel de accesibilidad
acceso abierto
Condiciones de uso
http://creativecommons.org/licenses/by-nc-sa/4.0/
Repositorio
SEDICI (UNLP)
Institución
Universidad Nacional de La Plata
OAI Identificador
oai:sedici.unlp.edu.ar:10915/123995

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oai_identifier_str oai:sedici.unlp.edu.ar:10915/123995
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repository_id_str 1329
network_name_str SEDICI (UNLP)
spelling Last giant impact on Uranus: constraints on oligarchic masses in the trans-Saturnian regionParisi, Mirta GabrielaCiencias AstronómicasPlanets and satellites: generalPlanets and satellites: formationContext. Modern models of the formation of ice giants attempt to account for the formation of Uranus and Neptune within the protoplanetary disk lifetime. These models assume a higher initial surface density well above that of the minimum mass solar nebula model and/or the formation of all giant planets in an inner compact configuration. Other effects include planetesimals migration due to gas drag and the small size of the accreted planetesimals, which accelerates the accretion rate. However, at present, none of these models account for the spin properties of the ice giants. Aims. Stochastic impacts by large bodies are, at present, the usually accepted mechanisms able to account for the obliquity of the ice giants. We attempt to set constraints on giant impacts as the cause of Uranus’s current obliquity of 98° and on the impactor masses. Methods. Since stochastic collisions among embryos are assumed to occur beyond oligarchy, we model the angular momentum transfer to proto-Uranus by the last stochastic collision (GC) between the protoplanet and an oligarchic mass at the end of Uranus’s formation. We take a minimum impactor mass m<sub>i</sub> of 1 m<sub>⊕</sub>. Results. We find that an oligarchic mass m<sub>i</sub> ~ 1 m⊕ ≤ m<sub>i</sub> ≤ 4.5 m<sub>⊕</sub> would be required at the GC to reproduce the present rotational properties of Uranus. An impact with m<sub>i</sub> > 4.5 m<sub>⊕</sub> is not possible, unless the impact parameter of the collision is very small and/or the angle between the spin axis of Uranus prior and after the GC is higher than 130°. This result is valid if Uranus formed in situ or between 10 − 20 AU and does not depend on the occurrence of the GC after or during the possible migration of the planet. This result is very similar to one obtained for Neptune from its rotational properties. Conclusions. If the stage of stochastic impacts among oligarchs has occurred and if the present rotational status of Uranus is the result of such processes, the 4.5 m<sub>⊕</sub> mass limit must be understood as an upper constraint on the oligarchic masses in the trans-Saturnian region at the end of ice giants’ formation. This result may be used to set constraints on planetary formation scenarios.Instituto Argentino de Radioastronomía2011info:eu-repo/semantics/articleinfo:eu-repo/semantics/publishedVersionArticulohttp://purl.org/coar/resource_type/c_6501info:ar-repo/semantics/articuloapplication/pdfhttp://sedici.unlp.edu.ar/handle/10915/123995enginfo:eu-repo/semantics/altIdentifier/issn/0004-6361info:eu-repo/semantics/altIdentifier/issn/1432-0746info:eu-repo/semantics/altIdentifier/doi/10.1051/0004-6361/201117085info:eu-repo/semantics/openAccesshttp://creativecommons.org/licenses/by-nc-sa/4.0/Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International (CC BY-NC-SA 4.0)reponame:SEDICI (UNLP)instname:Universidad Nacional de La Platainstacron:UNLP2025-09-29T11:29:29Zoai:sedici.unlp.edu.ar:10915/123995Institucionalhttp://sedici.unlp.edu.ar/Universidad públicaNo correspondehttp://sedici.unlp.edu.ar/oai/snrdalira@sedici.unlp.edu.arArgentinaNo correspondeNo correspondeNo correspondeopendoar:13292025-09-29 11:29:29.891SEDICI (UNLP) - Universidad Nacional de La Platafalse
dc.title.none.fl_str_mv Last giant impact on Uranus: constraints on oligarchic masses in the trans-Saturnian region
title Last giant impact on Uranus: constraints on oligarchic masses in the trans-Saturnian region
spellingShingle Last giant impact on Uranus: constraints on oligarchic masses in the trans-Saturnian region
Parisi, Mirta Gabriela
Ciencias Astronómicas
Planets and satellites: general
Planets and satellites: formation
title_short Last giant impact on Uranus: constraints on oligarchic masses in the trans-Saturnian region
title_full Last giant impact on Uranus: constraints on oligarchic masses in the trans-Saturnian region
title_fullStr Last giant impact on Uranus: constraints on oligarchic masses in the trans-Saturnian region
title_full_unstemmed Last giant impact on Uranus: constraints on oligarchic masses in the trans-Saturnian region
title_sort Last giant impact on Uranus: constraints on oligarchic masses in the trans-Saturnian region
dc.creator.none.fl_str_mv Parisi, Mirta Gabriela
author Parisi, Mirta Gabriela
author_facet Parisi, Mirta Gabriela
author_role author
dc.subject.none.fl_str_mv Ciencias Astronómicas
Planets and satellites: general
Planets and satellites: formation
topic Ciencias Astronómicas
Planets and satellites: general
Planets and satellites: formation
dc.description.none.fl_txt_mv Context. Modern models of the formation of ice giants attempt to account for the formation of Uranus and Neptune within the protoplanetary disk lifetime. These models assume a higher initial surface density well above that of the minimum mass solar nebula model and/or the formation of all giant planets in an inner compact configuration. Other effects include planetesimals migration due to gas drag and the small size of the accreted planetesimals, which accelerates the accretion rate. However, at present, none of these models account for the spin properties of the ice giants. Aims. Stochastic impacts by large bodies are, at present, the usually accepted mechanisms able to account for the obliquity of the ice giants. We attempt to set constraints on giant impacts as the cause of Uranus’s current obliquity of 98° and on the impactor masses. Methods. Since stochastic collisions among embryos are assumed to occur beyond oligarchy, we model the angular momentum transfer to proto-Uranus by the last stochastic collision (GC) between the protoplanet and an oligarchic mass at the end of Uranus’s formation. We take a minimum impactor mass m<sub>i</sub> of 1 m<sub>⊕</sub>. Results. We find that an oligarchic mass m<sub>i</sub> ~ 1 m⊕ ≤ m<sub>i</sub> ≤ 4.5 m<sub>⊕</sub> would be required at the GC to reproduce the present rotational properties of Uranus. An impact with m<sub>i</sub> > 4.5 m<sub>⊕</sub> is not possible, unless the impact parameter of the collision is very small and/or the angle between the spin axis of Uranus prior and after the GC is higher than 130°. This result is valid if Uranus formed in situ or between 10 − 20 AU and does not depend on the occurrence of the GC after or during the possible migration of the planet. This result is very similar to one obtained for Neptune from its rotational properties. Conclusions. If the stage of stochastic impacts among oligarchs has occurred and if the present rotational status of Uranus is the result of such processes, the 4.5 m<sub>⊕</sub> mass limit must be understood as an upper constraint on the oligarchic masses in the trans-Saturnian region at the end of ice giants’ formation. This result may be used to set constraints on planetary formation scenarios.
Instituto Argentino de Radioastronomía
description Context. Modern models of the formation of ice giants attempt to account for the formation of Uranus and Neptune within the protoplanetary disk lifetime. These models assume a higher initial surface density well above that of the minimum mass solar nebula model and/or the formation of all giant planets in an inner compact configuration. Other effects include planetesimals migration due to gas drag and the small size of the accreted planetesimals, which accelerates the accretion rate. However, at present, none of these models account for the spin properties of the ice giants. Aims. Stochastic impacts by large bodies are, at present, the usually accepted mechanisms able to account for the obliquity of the ice giants. We attempt to set constraints on giant impacts as the cause of Uranus’s current obliquity of 98° and on the impactor masses. Methods. Since stochastic collisions among embryos are assumed to occur beyond oligarchy, we model the angular momentum transfer to proto-Uranus by the last stochastic collision (GC) between the protoplanet and an oligarchic mass at the end of Uranus’s formation. We take a minimum impactor mass m<sub>i</sub> of 1 m<sub>⊕</sub>. Results. We find that an oligarchic mass m<sub>i</sub> ~ 1 m⊕ ≤ m<sub>i</sub> ≤ 4.5 m<sub>⊕</sub> would be required at the GC to reproduce the present rotational properties of Uranus. An impact with m<sub>i</sub> > 4.5 m<sub>⊕</sub> is not possible, unless the impact parameter of the collision is very small and/or the angle between the spin axis of Uranus prior and after the GC is higher than 130°. This result is valid if Uranus formed in situ or between 10 − 20 AU and does not depend on the occurrence of the GC after or during the possible migration of the planet. This result is very similar to one obtained for Neptune from its rotational properties. Conclusions. If the stage of stochastic impacts among oligarchs has occurred and if the present rotational status of Uranus is the result of such processes, the 4.5 m<sub>⊕</sub> mass limit must be understood as an upper constraint on the oligarchic masses in the trans-Saturnian region at the end of ice giants’ formation. This result may be used to set constraints on planetary formation scenarios.
publishDate 2011
dc.date.none.fl_str_mv 2011
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info:eu-repo/semantics/altIdentifier/issn/1432-0746
info:eu-repo/semantics/altIdentifier/doi/10.1051/0004-6361/201117085
dc.rights.none.fl_str_mv info:eu-repo/semantics/openAccess
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Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International (CC BY-NC-SA 4.0)
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rights_invalid_str_mv http://creativecommons.org/licenses/by-nc-sa/4.0/
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