Can asteroid fields ever exist locally in a system, or do they tend to form belts exclusively?
And by asteroid field, I mean clusters of asteroids scattered around a planetary system.
Can asteroid fields ever exist locally in a system, or do they tend to form belts exclusively?
And by asteroid field, I mean clusters of asteroids scattered around a planetary system.
I contend that the Trojan, Greek, and Hilda groups associated with Jupiter in our own solar system constitute "fields" as opposed to "belts." The Hildas are perhaps more scattered, but they do not fit the word "belt" as I assume you mean it. Certainly, the green and orange dots in this image seem far less belt-like than the white dots (the main asteroid belt) do:
image source: wikipedia
Each of these clusters is associated with one or more Lagrangian points of Jupiter, which more or less means these objects are locked in a gravitational dance with Jupiter, and orbit the sun in concert with Jupiter and each other.
Current theory is that planetary systems form via gravitational collapse of a cloud of material into a rotating disk, with resulting accretion and breakup of colliding masses within the disk. Zones where accretion forces did not produce a planet would end in a 'belt' of smaller objects. Gravitational resonance would shape the size and concentration of the belt, and would occasionally throw an object into an eccentric trajectory.
'Asteroids' will be found in belts aligned with the plane of the system. Concentrated fields will only be found in the vicinity of recently disintegrated large masses or in Lagrange points.