AST 248 Lecture Notes - Lecture 6: Planetesimal, Star Formation, Solar Thermal Collector
Document Summary
Dense cores of molecular clouds collapse into hot plasma which eventually triggers nuclear reactions. Conversion of gravitational energy both heats the material and releases infrared radiation. Dense clumps form in protostellar disc that eventually themselves collapse into planets. Conservation of angular momentum requires spin rate to increase during collapse and disc formation. Emissions of protostar hidden by cooler infalling matter; eventually breaks out at poles (least resistance), producing jets. Sufficiently rapidly rotating collapses form double or multiple stars. You(cid:374)g star"s e(cid:373)issio(cid:374)s s(cid:449)eep out gas a(cid:374)d dust fro(cid:373) pla(cid:374)etary syste(cid:373). Georges buffon suggested (1745) that the planets formed when a massive object (a comet, he thought) collided with the sun and splashed out debris that coalesced into planets. Immanuel kant proposed (1755) that the solar system formed from the gravitational collapse of an interstellar gas cloud. Pierre- i(cid:373)o(cid:374) lapla(cid:272)e (cid:894)(cid:1005)79(cid:1004)(cid:895) i(cid:374)depe(cid:374)de(cid:374)tly proposed ka(cid:374)t"s idea a(cid:374)d suggested pla(cid:374)ets for(cid:373)ed i(cid:374) successive rings of gas.