Astronomy 1021 Chapter 16: Chapter 16 Summary Cosmic Perspective
4 Jan 2012
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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 is going on inside them. How nuclear fusion begins in a newborn star: The flood of photons coming from an extremely massive star exerts radiation pressure that can drive a star s outer layers into interstellar space, this form of pressure blows apart stars with masses greater than about 150msun. Molecular clouds: cool, dense interstellar clouds in which low temperatures allow hydrogen atoms to pair up into hydrogen molecules. Thermal pressure: the ordinary pressure in a gas arising from motions of particles that can be attributed to the object s temperature. Protostar: a forming star that has not yet reached the point where sustainable fusion can occur in its core. Protostellar disk: a disk of material surrounding a protostar. Protostellar winds: a relatively strong wind from a protostar.
