The Physics Of Protoplanetesimal Dust Agglomerates. Viii. Microgravity Collisions Between Porous Sio2 Aggregates And Loosely Bound Agglomerates

Keywords

accretion, accretion disks; planets and satellites: formation; protoplanetary disks

Abstract

We performed laboratory experiments colliding 0.8-1.0 mm and 1.0-1.6 mm SiO2 dust aggregates with loosely bound centimeter-sized agglomerates of those aggregates in microgravity. This work builds on previous microgravity laboratory experiments examining the collisional properties of porous loosely bound dust aggregates. In centimeter-sized aggregates, surface forces dominate self-gravity and may play a large role in aggregate growth beyond this size range. We characterize the properties of protoplanetary aggregate analogs to help place constraints on initial formation mechanisms and environments. We determined several important physical characteristics of these aggregates in a large number of low-velocity collisions. We observed low coefficients of restitution and fragmentation thresholds near 1 m s-1 for 1-2 cm agglomerates, which are in good agreement with previous findings in the literature. We find the accretion efficiency for agglomerates of loosely bound aggregates to be higher than that for just aggregates themselves. We find sticking thresholds of 6.6 ± 2 cm s-1, somewhat higher than those in similar studies, which have observed few aggregates stick at speeds of under 3 cm s-1. Even with highly dissipative collisions, loosely bound agglomerates have difficulty accreting beyond centimeter-sized bodies at typical collision speeds in the disk. Our results indicate agglomerates of porous aggregates have slightly higher sticking thresholds than previously thought, allowing possible growth to decimeter-sized bodies if velocities are low enough.

Publication Date

2-10-2017

Publication Title

Astrophysical Journal

Volume

836

Issue

1

Document Type

Article

Personal Identifier

scopus

DOI Link

https://doi.org/10.3847/1538-4357/836/1/94

Socpus ID

85014167213 (Scopus)

Source API URL

https://api.elsevier.com/content/abstract/scopus_id/85014167213

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