Material Growth in the Early Solar System
Channel: Dominik Hezel
Date: 2023-04-12

Our Solar System formed from a molecular cloud of about one light year in diameter. Such molecular clouds consist primarily of gas, but also interstellar material. These are sub-µm small grains. Subsequent to the collapse of the molecular cloud, a protoplanetary disk forms around forming Sun, in which the first of 3 discrete growth steps proceeds. The sub-µm small interstellar grains grow to hundreds of µm to mm sized grains, the chondrules. Further µm to tens of µm sized material form and constitute the matrix of the chondrites. This material, however, was certainly also produced on asteroids during alteration processes. In the second growth step, chondrules and matrix agglomerated into m to km sized planetesimals, including minor components such as CAIs and opaque phases. During this time the protoplanetary disk dissolves, and the asteroids orbit the sun on Keplerian paths. In the final third growth step these asteroids collide and aggregate into hundreds of thousands km sized planets. Only these there discrete growth steps were necessary to build planets across 10-15 orders of magnitude from sub-µm small interstellar grains.