Collisional growth of organic-mantled grains and formation of rocky planetesimals
Abstract
It is believed that the collisional growth of silicate dust grains is restricted by their poor stickiness. In this study, we explore the possibility that the stickiness of silicate grains in protoplanetary disks is enhanced by organic mantles. Silicate grains coated by organics can be commonly found in interplanetary dust particles, and previous laboratory experiments (Kudo et al. 2002) showed that such organic-coated particles are sticky in warm environments. To study in more detail how the stickiness of organic-mantled grains depends on temperature and mantle thickness, we construct a simple grain adhesion model that gives the binding energy of core-mantle grains in contact. Our model shows that the stickiness of organic-mantled grains increases with temperature. This occurs because as the temperature increases, the elasticity of organic mantles decreases and the contact area increases. We find that aggregates made of organic-coated grains are able to break through the fragmentation barrier in the inner part of protoplanetary disks where temperature is above > 200 K. We also simulate the growth and radial drift of organic-mantled grains in a disk, finding that they indeed grow into planetesimal-sized objects in a warm inner region of the disk. We will discuss a new scenario for terrestrial planet formation based on our results. Reference: Homma, A. K. et al. 2019, ApJ, 877, 128 (DOI: 10.3847/1538-4357/ab1de0)
- Publication:
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AAS/Division for Extreme Solar Systems Abstracts
- Pub Date:
- August 2019
- Bibcode:
- 2019ESS.....431703H