Polydisperse streaming instability – III. Dust evolution encourages fast instability

Planet formation via core accretion requires the production of km-sized planetesimals from cosmic dust. This process must overcome barriers to simple collisional growth, for which Streaming Instability (SI) is often invoked. Dust evolution still required create particles large enough undergo vigorous instability. The SI has been studied primarily with single size dust, and role full evolved dust distribution largely unexplored. We survey Polydispserse (PSI) physical parameters corresponding plausible conditions in protoplanetary discs. consider a range particle stopping times, generalized distributions, effect turbulence. find that, while PSI grows many cases more slowly interstellar power-law than size, reasonable evolution, producing an enhancement largest sizes, produces instability behaviour similar monodisperse case. Considering turbulent diffusion trend similar. conclude that if fast linear growth planet formation, then peak times on order 0.1 orbits significantly above produced by fragmentation cascade sufficient, along local gas volume mass density ratio unity.