Chondrule Formation via Impact Jetting Triggered by Planetary Accretion

Abstract

Chondrules are one of the most primitive elements that can serve as a fundamental clue as to the origin of our Solar system. We investigate a formation scenario of chondrules that involves planetesimal collisions and the resultant impact jetting. Planetesimal collisions are the main agent to regulate planetary accretion that corresponds to the formation of terrestrial planets and cores of gas giants. The key component of this scenario is that ejected materials can melt when the impact velocity between colliding planetesimals exceeds about 2.5 km s${}^{-1}$. The previous simulations show that the process is efficient enough to reproduce the primordial abundance of chondrules. We examine this scenario carefully by performing semi-analytical calculations that are developed based on the results of direct $N$-body simulations. As found by the previous work, we confirm that planetesimal collisions that occur during planetary accretion can play an important role in forming chondrules. This arises because protoplanet-planetesimal collisions can achieve the impact velocity of about 2.5 km s${}^{-1}$ or higher, as protoplanets approach the isolation mass ($M_{p,iso}$). Assuming that the ejected mass is a fraction ($F_{ch}$) of colliding planetesimals' mass, we show that the resultant abundance of chondrules is formulated well by $F_{ch}{M}_{p,iso}$, as long as the formation of protoplanets is completed within a given disk lifetime. We perform a parameter study and examine how the abundance of chondrules and their formation timing change. We find that the impact jetting scenario generally works reasonably well for a certain range of parameters, while more dedicated work would be needed to include other physical processes that are neglected in this work and to examine their effects on chondrule formation.

14 pages, 8 figures, 1 table, accepted for publication in ApJ

References in corpus (6)

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• Accretion and destruction of planetesimals in turbulent disks
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Cited by in corpus (12)

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• Relativistic Magnetic Reconnection in Astrophysical Plasmas: A Powerful Mechanism of Nonthermal Emission
• Thermal History Of Cbb Chondrules And Cooling Rate Distributions Of Ejecta Plumes
• Planetesimal collisions as a chondrule forming event
• Forming Chondrites in a Solar Nebula with Magnetically Induced Turbulence
• Chondrules from high-velocity collisions: thermal histories and the agglomeration problem
• Aggregate Growth and Internal structures of Chondrite Parent Bodies Forming from Dense Clumps
• The Properties of Planetesimal Collisions under Jupiter's Perturbation and the Application to Chondrule Formation via Impact Jetting
• Abundances of ordinary chondrites in thermally evolving planetesimals
• Chondrule Accretion with a Growing Protoplanet
• Chondrule formation by collisions of planetesimals containing volatiles triggered by Jupiter's formation