ISP Chapter 14 Our Galaxy

ISP Chapter 14 Our Galaxy - Chapter 14 Our Galaxy ? What...

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Chapter 14 Our Galaxy ? What does our galaxy look like (from the outside)? -a disk of stars, organized into “arms” The Milky Way galaxy appears in our sky as a faint band of light Dusty gas clouds obscure our view because they absorb visible light These interstellar clouds are where new stars form This gas is the interstellar medium that makes new star systems (black spaces) Primary features: o Bulge o Disk: different age stars, very thin but wide o Halo: not many stars, but very old o Globular clusters: all born at one time, snapshot at single age Spiral arms like “traffic jams” HOW DO STARS ORBIT IN OUR GALAXY Stars in the disk all orbit in the same direction with a little up-and-down motion Orbits of stars in bulge and halo have random orientations ? Why do orbits of disk stars bob up and down? -gravity of disk stars pulls toward disk The sun’s orbital motion (radius and velocity) tells us the galaxy’s mass within Sun’s orbit: o 1.0x 10 11 M sun Milky way has quite a bit of “black
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This note was uploaded on 11/16/2011 for the course ISP 205 taught by Professor Donahue during the Fall '08 term at Michigan State University.

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ISP Chapter 14 Our Galaxy - Chapter 14 Our Galaxy ? What...

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