What characteristic was crucial for collisions between orbiting planetesimals to facilitate growth rather than destruction?

Answer

They needed to be sticky or gently inelastic

The success of planetary formation via this route hinges on the nature of the physical interactions between the accumulating planetesimals. If collisions were entirely destructive, shattering the growing bodies back into microscopic debris, growth would cease. Therefore, the collisions needed a degree of 'stickiness' or inelasticity, allowing some material to merge upon impact due to molecular forces or slight gravitational capture, resulting in a slightly larger object. This small gain allowed gravity to eventually take over more effectively as objects scaled up.

What characteristic was crucial for collisions between orbiting planetesimals to facilitate growth rather than destruction?
astronomyplanet formationplanetesimal theory