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