AST201H1 Chapter Notes - Chapter 16: Molecular Cloud, Degenerate Matter, Distant Star

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

Document Summary

The gas and dust that fill the spaces between stars within a galaxy as the interstellar medium. The interstellar medium consists (by mass) of 70/ hydrogen, 28/ helium, and 2/ heavier elements. Stars are born interstellar clouds that are particularly cold and dense. These clouds are usually called molecular clouds because they are cold enough and dense enough to allow atoms to combine together into molecules. Molecular hydrogen is difficult to detect, because molecular clouds are usually too cold for h2 to produce emission lines. Carbon monoxide (co) is the most abundant of these molecules, and it produces radio emission lines that allow us to map the structures of molecular clouds. About half the atoms of elements heavier than helium are found in tiny, solid grains of interstellar dust. Dust grains scatter or absorb virtually all the visible light that enters a molecular cloud, preventing us from seeing stars that lie behind it.