AST201H1 Chapter Notes - Chapter 16: Molecular Cloud, Protostar, Degenerate Matter

• School: UTSG
• Department: Astronomy & Astrophysics
• Course: AST201H1
• Professor: Michael Reid

Document Summary

Stars form in cold, relatively dense molecular clouds. Solid grains of interstellar dust prevent visible light from passing through these clouds, but we can use infrared observations to see what"s going on inside them. A star can form in molecular cloud only when gravity is strong enough to overpower the outward push of thermal pressure. Stars tend to form in clusters because gravity can more easily overcome pressure in more massive molecular clouds. A large cloud fragments into many smaller clumps of gas as it contracts, because the advantage of gravity over pressure increases as a clump of gas shrinks in size. What slows the contraction of a star-forming cloud: A contracting cloud begins its transformation into a star when its core stars trapping the thermal energy released by gravitational contraction. As pressure begins to push back harder, the contraction slows down and the central part of the cloud becomes a protostar.