Young star clusters give insight into star formation and evolution

Young star clusters give insight into star formation and evolution

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Young star clusters give insight into star formation and evolution • Newborn stars may form an open or galactic cluster • Stars are held together in such a cluster by gravity • Occasionally a star moving more rapidly than average will escape, or “evaporate,” from such a cluster • A stellar association is a group of newborn stars that are moving apart so rapidly that their gravitational attraction for one another cannot pull them into orbit about one another Star birth can begin in giant molecular clouds • The spiral arms of our Galaxy are laced with giant molecular clouds, immense nebulae so cold that their constituent atoms can form into molecules. • Star-forming regions appear when a giant molecular cloud is compressed • This can be caused by the cloud’s passage through one of the spiral arms of our Galaxy,
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Unformatted text preview: by a supernova explosion, or by other mechanisms • O and B Stars and Their Relation to H II Regions • The most massive protostars to form out of a dark nebula rapidly become main sequence O and B stars • They emit strong ultraviolet radiation that ionizes hydrogen in the surrounding cloud, thus creating the reddish emission nebulae called H II regions • Ultraviolet radiation and stellar winds from the O and B stars at the core of an H II region create shock waves that move outward through the gas cloud, compressing the gas and triggering the formation of more protostars. • Supernovae compress the interstellar medium and can trigger star birth...
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This note was uploaded on 12/15/2011 for the course AST AST1002 taught by Professor Emilyhoward during the Fall '10 term at Broward College.

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