dust trap

The term dust trap is used for mechanisms within protoplanetary disks that cause dust to gather and remain in proximity, giving more chance to any mechanism that causes grains to stick together. Such dust trap mechanisms have been theorized to overcome some of the theoretical planet formation barriers. One theory is that extra dust in a portion of the disk causes a local increase in the gas pressure, and that dust tends to migrate to the portions with the highest pressure. This would be runaway process, I would imagine until the gas pressure differences counteract the tendency. Presumably the dust density in the location grows high enough to begin forming solid objects.