Unformatted text preview: arms of our Galaxy, 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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- Fall '10
- Astronomy, Interstellar medium, Giant molecular clouds, giant molecular cloud, Newborn Stars