Formation of rims around chondrules via porous aggregate accretion

1Yuji Matsumoto,2Yasuhiro Hasegawa,3Nozomi Matsuda,3Ming-Chang Liu
Icarus (in Press) Link to Article [https://doi.org/10.1016/j.icarus.2021.114538]
1Institute of Astronomy and Astrophysics, Academia Sinica, No.1, Sec. 4, Roosevelt Rd, Taipei 10617, Taiwan
2Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA
3Department of Earth, Planetary, and Space Sciences, University of California, Los Angeles, CA, USA
Copyright Elsevier

Chondrules are often surrounded by fine-grained rims or igneous rims. The properties of these rims reflect their formation histories. While the formation of fine-grained rims is modeled by the accretion of dust grains onto chondrules, the accretion should be followed by the growth of dust grains due to the shorter growth timescale than the accretion. In this paper, we investigate the formation of rims, taking into account the growth of porous dust aggregates. We estimate the rim thickness as a function of the chondrule fraction at a time when dust aggregate accretion onto chondrules is switched to collisions between these chondrules. Our estimations are consistent with the measured thicknesses of fine-grained rims in ordinary chondrites. However, those of igneous rims are thicker than our estimations. The thickness of igneous rims would be enlarged in remelting events.

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