AST 111 Lecture Notes - Lecture 9: Molecular Cloud, Supernova Remnant, Orbital Speed
18 Dec 2020
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Document Summary
Looking at our galaxy edge on reveals key features: disk, bulge, halo, globular clusters; view from above to see spiral arms. Stars in the disk orbit in the same direction with some up-and-down motion; stars in the bulge and halo have random orientations, and are positions high above and far below the disk. They bob up and down due to gravity. Orbital velocity law = the orbital speed (v) and radius (r) of an object on a circular orbit around the galaxy tell us the mass (mr) within that orbit. Gas is recycled in our gas through the star-gas-star cycle (old star gas into new stars) High-mass stars have strong stellar winds that blow bubbles out of hot gas. Lower-mass stars return gas to interstellar space through stellar winds and planetary nebulae. X-rays from hot gas in supernova remnants reveal newly made heavy elements, which mix into the interstellar medium.
