Seeding the Formation of Mercurys: An Iron-sensitive Bouncing Barrier in Disk Magnetic Fields

The inner part of protoplanetary disks can be threaded by strong magnetic fields. In laboratory levitation experiments, we study how magnetic fields up to 7 mT influence the aggregation of dust by observing the self-consistent collisional evolution of particle ensembles. As dust samples we use mixtu...

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Bibliographic Details
Published in:The Astrophysical journal 2018-12, Vol.869 (1), p.45
Main Authors: Kruss, Maximilian, Wurm, Gerhard
Format: Article
Language:English
Subjects:
Aggregates
Astrophysics
Bouncing
Clustering
Dust
Iron
Levitation
Magnetic fields
Magnetism
Mercury
Mercury (planet)
Planet formation
planets and satellites: formation
Protoplanetary disks
Protoplanets
Quartz
Solar system
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Summary:The inner part of protoplanetary disks can be threaded by strong magnetic fields. In laboratory levitation experiments, we study how magnetic fields up to 7 mT influence the aggregation of dust by observing the self-consistent collisional evolution of particle ensembles. As dust samples we use mixtures of iron and quartz in different ratios. Without magnetic fields, particles in all samples grow into a bouncing barrier. These aggregates reversibly form larger clusters in the presence of magnetic fields. The size of these clusters depends on the strength of the magnetic field and the ratio between iron and quartz. The clustering increases the size of the largest entities by a factor of a few. If planetesimal formation is sensitive to the size of the largest aggregates, e.g., relying on streaming instabilities, then planetesimals will preferentially grow iron-rich in the inner region of protoplanetary disks. This might explain the iron gradient in the solar system and the formation of dense Mercury-like planets.
ISSN:0004-637X
1538-4357
DOI:10.3847/1538-4357/aaec78