AST101H1 Chapter 16: Chapter 16_ the Birth of a Star
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AST101H1 Full Course Notes
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Document Summary
Technique of main-sequence turnoff point used to determine ages of star clusters. Youngest clusters always associated with dark clouds of gas and dust. Gas and dust found between stars called interstellar medium. Spectroscopy tells us the chemical contents of the cloud. Stars born in cold and dense interstellar clouds called molecular clouds (cold enough and dense enough to allow atoms to combine into molecules) Molecular hydrogen is most abundant, but difficult to detect as they are usually too cold to produce emission lines. Carbon monoxide of the clouds used to produce radio emission lines to map structures of molecular clouds. Elements like carbon, silicon, oxygen, and iron found as tiny solid grains of interstellar dust. About 1% of a molecular cloud"s mass. Prevents visible light from passing through cloud center (thus we require infrared images to see the star behind the cloud) Stars near the edge of a molecular cloud appear redder than those outside phenomenon named interstellar reddening.
