Merging Criteria for Planetesimal Collisions

In the standard scenario of planet formation, terrestrial planets, ice giants, and cores of gas giants are formed by the accumulation of planetesimals. However, there are few N -body simulation studies of planetesimal accretion that correctly take into account the merging condition of planetesimals....

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Bibliographic Details
Published in:The Astrophysical journal 2021-11, Vol.921 (2), p.163
Main Authors: Shibata, Takashi, Kokubo, Eiichiro, Hosono, Natsuki
Format: Article
Language:English
Subjects:
Astrophysics
Criteria
Deposition
Escape velocity
Exoplanets
Gas giant planets
Hydrodynamics
Ice formation
Ice giant planets
Impact angle
Impact velocity
Mass ratios
Planet formation
Planets
Smooth particle hydrodynamics
Solar system
Solar system planets
Terrestrial planets
Velocity
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Summary:In the standard scenario of planet formation, terrestrial planets, ice giants, and cores of gas giants are formed by the accumulation of planetesimals. However, there are few N -body simulation studies of planetesimal accretion that correctly take into account the merging condition of planetesimals. In order to investigate a realistic accretion process of planetesimals, it is necessary to clarify the merging criteria of planetesimals at collision. We perform numerical collision experiments using smoothed particle hydrodynamics and obtain the merging criteria as a function of planetesimal mass and impact parameters for undifferentiated rocky and icy planetesimals and differentiated icy planetesimals. We vary the total mass of colliding planetesimals, their mass ratios, and the impact angle and obtain the critical impact velocity as the merging criteria distinguishing merging from hit-and-run collision. We find that the critical impact velocity normalized by the two-body surface escape velocity decreases with increasing impact angle. The critical impact velocity does not depend on the total mass, while it has a weak positive dependence on the mass ratio. These results barely depend on the composition and internal structure of the planetesimals.
ISSN:0004-637X
1538-4357
DOI:10.3847/1538-4357/ac1e98