Galaxies

Question 1

Galaxy

Answer 1

Clear System of Gas and Stars

Question 2

Types of Galaxies

Answer 2

Spiral, Elliptical, & Irregular

Question 3

What influences the shape of Galaxies?

Answer 3

How organized the orbit of stars are within a galaxy.

Question 4

What influences shape of Spiral Galaxy?

Answer 4

Stars in disk of Spiral Galaxies orbit in sync; All Stars go around the Galaxy in similar orbits.

Question 5

What influences the shape of Elliptical Galaxies?

Answer 5

Stars move in random orbits, orientations, and sizes; Complex, irregular orbits; In all directions

Question 6

Bulge and Halo objects orbit in ____

Answer 6

Random directions

Question 7

What do Blue Stars indicate in a galaxy?

Answer 7

1. O & B Stars
2. Short-lived; formed recently
3. Active Star formation

Question 8

Visible Red Stars humans see are ____

Answer 8

Red Giants

Question 9

What type of stars are in spiral galaxies? Where are they located?

Answer 9

Disk: Blue Stars; where Star formation occurs
Bulge: Red Stars (Population II stars)
Halo: Star Clusters and Older Stars

Question 10

Spiral Arms

Answer 10

Parts of the disk with areas of hot (ionized) and cold gas.

Question 11

What is theorized about Spiral Arms?

Answer 11

Wave of Star formation traveling around disk.

Question 12

Physics Between Gas and Stars in Galaxy

Answer 12

1. Gas can easily sink; stars cannot (friction)
   - Gas loses energy, causing sinkage
2. Stars cannot lose kinetic energy; they preserve kinetic energy & angular momentum
3. Stars do not collide
4. Dark Matter acts like Stars

Question 13

What do disks in galaxies indicate?

Answer 13

Gas was left over from halo formation.

Question 14

When do Spiral Galaxies form?

Answer 14

When halo formation does not use up all the gas; Gas turns into stars slowly.

Question 15

When do Elliptical Galaxies form?

Answer 15

All Gas turns into starts quickly; No gas left to form disk

Question 16

What determines the type of galaxy formed?

Answer 16

Initial Star formation rate

Question 17

What are the two types of Star Populations?

Answer 17

Population I - Younger population of stars enriched with metals (More Metals! - elements heavier than helium)
Population II - Older population of stars with simpler elements (Hydrogen & Helium)

Question 18

What population of stars do parts of Galaxy form?

Answer 18

Halo - Population II
Disk - Population I

Question 19

How are Population I stars formed?

Answer 19

Formed from enriched gas that is returned from Stars fusing Hydrogen and heavier elements.

Question 20

What happens in Galaxy formation?

Answer 20

Big Cloud of Dark Matter & Gas -> Gas Collapses -> Stars Form -> Stars remain (do not move)