Astronomy Exam 4 Study Guide
Beginning at a star's birth, the next key stage in the star-gas-star cycle occurs when a(n) ____ returns gas and new elements into space.
supernova
The disk of the milky way is about ____ in diameter and ____ thick.
100,000 light years ; 1000 light years
As the gas in the bubble cools and merges with other interstellar gasses, it forms a(n) ____ .
atomic hydrogen cloud
Halo stars formed ____ disk stars. (before or after)
before
The expelled gas from a supernova forms a(n) ____ that is very hot and expanding in size.
bubble
Star formation occurs primarily in the galaxy's what?
disk
Our galaxy consists of a large, nearly flat ____ with a central ____ , all surrounded by a vast ____ .
disk; bulge; halo
We find ____ of stars mostly in the halo.
globular clusters
The protogalactic cloud(s) contained essentially no elements besides ____ .
hydrogen and helium
We refer to the gas and dust that resides in our galaxy as what?
interstellar medium
Further cooling allows the gas to become a(n) ____ , in which star formation occurs.
molecular cloud
What are spiral arms?
regions of active star formation
From our location, we cannot see far into the disk with ____ because our view is blocked by ____.
visible light ; dark dusty clouds