Rapid planetesimal formation in the inner protoplanetary disk

Growth barriers, including the bouncing, fragmentation and radial drift problems, are still a big issue in planetesimal and thus planet formation theory. We present a new mechanism for very rapid planetesimal formation by sweep-up growth. Planetesimal formation is extremely fast in the inner protoplanetary disk where the growth rate exceeds the radial drift rate, leading to local planetesimal formation and pile-up inside of 1 AU. This scenario is very appealing particularly in the context of explaining the low mass of Mars, as well as the formation of recently discovered multi-transiting systems with tightly-packed inner planets.