PHYSICS 20A Lecture Notes - Lecture 15: Kuiper Belt, Protoplanetary Disk, Accretion Disk
Document Summary
Physics 20a lecture 15 star & planet formation. Within a cloud, there are some denser regions. As the cloud collapses, the denser regions collapse faster and become more massive. The densest regions form molecular cloud cores that can collapse into stars: they form protostars, young stars. As the cloud collapses to a smaller size, it rotates faster. The protostar forms at the center of the rotating cloud: it grows more massive as more gas accretes into it. Surrounding the protostar is an accretion disk: rotating disk of gas that is gradually drifting inward and adding to the mass of the protostar, protoplanetary disk. Where all the planets and other objects roam. As the little pieces blow faster, they run into the slower large particles. Remnants of the formation process: asteroids. Rocky bodies with sizes ranging up to ~1000km. Planetesimals left from the formation of solar system, or fragments of planetesimals blasted apart in collisions.
