摘要：AbstractWe studied the particle growth in a protoplanetary disk in a high-ionization environment and found that icy planet formation is inactive for a disk with an ionization rate 100 times higher than that of the present Solar System. In particular, in the case ofM˙<10−7.4M⊙yr−1, only rocky planet formation occurs. In such a case, all the solid materials in the disk drift inward, eventually reach the inner MRI front, and accumulate there. They form a dense, thin sub-disk of solid particles, which undergoes gravitational instability to form rocky planetesimals. The planetesimals rapidly grow into a planet through pebble accretion. Consequently, rocky planets tend to be much larger than planets formed through other regimes (tandem planet formation regime and dispersed planet formation regime), in which icy planet formation actively takes place. These rocky planets may evolve into hot Jupiters if they grow fast enough to the critical core mass of the runaway gas accretion before the dispersal of the disk gas, or they may evolve into super-Earths if the gas dispersed sufficiently early.Graphical abstractDisplay OmittedHighlights•Planet-formation regime with high ionization rate due to the galactic cosmic rays.•Magneto-rotational instability (MRI) and porous aggregation are taken into account.•The outer MRI front is located inside the water sublimation zone.•The formation of icy planetesimals in the icy region is rare.•This regime accounts for the formation of hot Jupiters and super-Earths around 0.1–1 AU.
