Size–Frequency Distribution of Terrestrial Leftover Planetesimals and S-complex Implanted Asteroids

The isotopic composition of meteorites linked to S-complex asteroids has been used to suggest that these asteroids originated in the terrestrial planet’s region, i.e., within 1.5 au, and later got implanted into the main asteroid belt (MAB). Dynamical models of planet formation support this view. Ye...

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Main Authors: Rogerio Deienno, André Izidoro, David Nesvorný, William F. Bottke, Fernando Roig, Simone Marchi
Format: Article
Language:English
Published: IOP Publishing 2025-01-01
Series:The Astrophysical Journal
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Online Access:https://doi.org/10.3847/1538-4357/adccbb
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author Rogerio Deienno
André Izidoro
David Nesvorný
William F. Bottke
Fernando Roig
Simone Marchi
author_facet Rogerio Deienno
André Izidoro
David Nesvorný
William F. Bottke
Fernando Roig
Simone Marchi
author_sort Rogerio Deienno
collection DOAJ
description The isotopic composition of meteorites linked to S-complex asteroids has been used to suggest that these asteroids originated in the terrestrial planet’s region, i.e., within 1.5 au, and later got implanted into the main asteroid belt (MAB). Dynamical models of planet formation support this view. Yet it remains to be demonstrated whether the currently observed size–frequency distribution (SFD) of S-complex bodies in the MAB can be reproduced via this implantation process. Here we studied the evolution of the SFD of planetesimals during the accretion of terrestrial planets with the code LIPAD self-consistently accounting for growth and fragmentation of planetesimals. In our simulations we vary the initial surface density of planetesimals, the gaseous disk lifetime, and the power slope of the initial planetesimals’ SFD. We compared the final SFDs of leftover planetesimals in the terrestrial planet region with the SFD of observed S-complex MAB objects ( D > 100 km). We found that the SFDs of our planetesimal populations and that of S-complex MAB objects show very similar cumulative power index (i.e., q ≈ 3.15 in N (> D ) ∝ D ^− ^q ) for slopes in the diameter range 100 km < D < 400 km by the end of our simulations. Our results support the hypothesis of S-complex MAB implantation from the terrestrial planet forming region, assuming implantation is size independent, and imply that implantation efficiency is smaller than ${ \mathcal O }$ (10 ^–2 –10 ^–4 ) to avoid overimplantation of (4) Vesta-sized objects or larger.
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spelling doaj-art-ac2bd967de404143a3ee31dc902ca2152025-08-20T02:33:16ZengIOP PublishingThe Astrophysical Journal1538-43572025-01-01986214610.3847/1538-4357/adccbbSize–Frequency Distribution of Terrestrial Leftover Planetesimals and S-complex Implanted AsteroidsRogerio Deienno0https://orcid.org/0000-0001-6730-7857André Izidoro1https://orcid.org/0000-0003-1878-0634David Nesvorný2https://orcid.org/0000-0002-4547-4301William F. Bottke3https://orcid.org/0000-0002-1804-7814Fernando Roig4https://orcid.org/0000-0001-7059-5116Simone Marchi5https://orcid.org/0000-0003-2548-3291Solar System Science & Exploration Division, Southwest Research Institute , 1301 Walnut Street, Suite 400, Boulder, CO 80302, USA ; rogerio.deienno@swri.orgDepartment of Earth, Environmental and Planetary Sciences, MS 126, Rice University , Houston, TX 77005, USASolar System Science & Exploration Division, Southwest Research Institute , 1301 Walnut Street, Suite 400, Boulder, CO 80302, USA ; rogerio.deienno@swri.orgSolar System Science & Exploration Division, Southwest Research Institute , 1301 Walnut Street, Suite 400, Boulder, CO 80302, USA ; rogerio.deienno@swri.orgObservatório Nacional , Rua General José Cristino 77, Rio de Janeiro, RJ 20921-400, BrazilSolar System Science & Exploration Division, Southwest Research Institute , 1301 Walnut Street, Suite 400, Boulder, CO 80302, USA ; rogerio.deienno@swri.orgThe isotopic composition of meteorites linked to S-complex asteroids has been used to suggest that these asteroids originated in the terrestrial planet’s region, i.e., within 1.5 au, and later got implanted into the main asteroid belt (MAB). Dynamical models of planet formation support this view. Yet it remains to be demonstrated whether the currently observed size–frequency distribution (SFD) of S-complex bodies in the MAB can be reproduced via this implantation process. Here we studied the evolution of the SFD of planetesimals during the accretion of terrestrial planets with the code LIPAD self-consistently accounting for growth and fragmentation of planetesimals. In our simulations we vary the initial surface density of planetesimals, the gaseous disk lifetime, and the power slope of the initial planetesimals’ SFD. We compared the final SFDs of leftover planetesimals in the terrestrial planet region with the SFD of observed S-complex MAB objects ( D > 100 km). We found that the SFDs of our planetesimal populations and that of S-complex MAB objects show very similar cumulative power index (i.e., q ≈ 3.15 in N (> D ) ∝ D ^− ^q ) for slopes in the diameter range 100 km < D < 400 km by the end of our simulations. Our results support the hypothesis of S-complex MAB implantation from the terrestrial planet forming region, assuming implantation is size independent, and imply that implantation efficiency is smaller than ${ \mathcal O }$ (10 ^–2 –10 ^–4 ) to avoid overimplantation of (4) Vesta-sized objects or larger.https://doi.org/10.3847/1538-4357/adccbbAsteroid beltAsteroid dynamicsSolar system formationSolar system terrestrial planets
spellingShingle Rogerio Deienno
André Izidoro
David Nesvorný
William F. Bottke
Fernando Roig
Simone Marchi
Size–Frequency Distribution of Terrestrial Leftover Planetesimals and S-complex Implanted Asteroids
The Astrophysical Journal
Asteroid belt
Asteroid dynamics
Solar system formation
Solar system terrestrial planets
title Size–Frequency Distribution of Terrestrial Leftover Planetesimals and S-complex Implanted Asteroids
title_full Size–Frequency Distribution of Terrestrial Leftover Planetesimals and S-complex Implanted Asteroids
title_fullStr Size–Frequency Distribution of Terrestrial Leftover Planetesimals and S-complex Implanted Asteroids
title_full_unstemmed Size–Frequency Distribution of Terrestrial Leftover Planetesimals and S-complex Implanted Asteroids
title_short Size–Frequency Distribution of Terrestrial Leftover Planetesimals and S-complex Implanted Asteroids
title_sort size frequency distribution of terrestrial leftover planetesimals and s complex implanted asteroids
topic Asteroid belt
Asteroid dynamics
Solar system formation
Solar system terrestrial planets
url https://doi.org/10.3847/1538-4357/adccbb
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