TY - JOUR
T1 - Chondrules from high-velocity collisions
T2 - Thermal histories and the agglomeration problem
AU - Choksi, Nick
AU - Chiang, Eugene
AU - Connolly, Harold C.
AU - Gainsforth, Zack
AU - Westphal, Andrew J.
N1 - Funding Information:
We thank Sarah Stewart for an inspiring talk that motivated this work, Steve Desch for an insightful referee report that led to qualitative changes to our paper, and Jeffrey Fung for prompting us to consider the effects of the nebular headwind and sharing his numerical simulations of solid/gas interactions. We thank Erik Asphaug, Bill Bottke, Don Brownlee, Linda Elkins-Tanton, Sivan Ginzburg, Brandon Johnson, Philipp Kempski, Sasha Krot, Rixin Li, Tomoki Nakamura, Laura Schaefer, Shigeru Wakita, Ben Weiss, and Andrew Youdin for useful exchanges. We are also grateful to the many people we talked with over the years about chondrules, including Jay Melosh. This work used the MATPLOTLIB (Hunter 2007) and SCIPY (Virtanen et al. 2020) packages, and was supported by National Aeronautics and Space Administration grant NNX15AD95G/NEXSS and Berkeley’s Esper Larsen, Jr. fund.
Publisher Copyright:
© 2021 The Author(s)
PY - 2021/5/1
Y1 - 2021/5/1
N2 - We assess whether chondrules, once-molten mm-sized spheres filling the oldest meteorites, could have formed from super-km s−1 collisions between planetesimals in the solar nebula. High-velocity collisions release hot and dense clouds of silicate vapour which entrain and heat chondrule precursors. Thermal histories of CB chondrules are reproduced for colliding bodies ∼10-100 km in radius. The slower cooling rates of non-CB, porphyritic chondrules point to colliders with radii ≳ 500 km. How chondrules, collisionally dispersed into the nebula, agglomerated into meteorite parent bodies remains a mystery. The same orbital eccentricities and inclinations that enable energetic collisions prevent planetesimals from re-accreting chondrules efficiently and without damage; thus the sedimentary laminations of the CB/CH chondrite Isheyevo are hard to explain by direct fallback of collisional ejecta. At the same time, planetesimal surfaces may be littered with the shattered remains of chondrules. The micron-sized igneous particles recovered from comet 81P/Wild-2 may have originated from in-situ collisions and subsequent accretion in the proto-Kuiper belt, obviating the need to transport igneous solids across the nebula. Asteroid sample returns from Hayabusa2 and OSIRIS-REx may similarly contain chondrule fragments.
AB - We assess whether chondrules, once-molten mm-sized spheres filling the oldest meteorites, could have formed from super-km s−1 collisions between planetesimals in the solar nebula. High-velocity collisions release hot and dense clouds of silicate vapour which entrain and heat chondrule precursors. Thermal histories of CB chondrules are reproduced for colliding bodies ∼10-100 km in radius. The slower cooling rates of non-CB, porphyritic chondrules point to colliders with radii ≳ 500 km. How chondrules, collisionally dispersed into the nebula, agglomerated into meteorite parent bodies remains a mystery. The same orbital eccentricities and inclinations that enable energetic collisions prevent planetesimals from re-accreting chondrules efficiently and without damage; thus the sedimentary laminations of the CB/CH chondrite Isheyevo are hard to explain by direct fallback of collisional ejecta. At the same time, planetesimal surfaces may be littered with the shattered remains of chondrules. The micron-sized igneous particles recovered from comet 81P/Wild-2 may have originated from in-situ collisions and subsequent accretion in the proto-Kuiper belt, obviating the need to transport igneous solids across the nebula. Asteroid sample returns from Hayabusa2 and OSIRIS-REx may similarly contain chondrule fragments.
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U2 - 10.1093/mnras/stab503
DO - 10.1093/mnras/stab503
M3 - Article
AN - SCOPUS:85111508011
VL - 503
SP - 3297
EP - 3308
JO - Monthly Notices of the Royal Astronomical Society
JF - Monthly Notices of the Royal Astronomical Society
SN - 0035-8711
IS - 3
ER -