Unit 11: Galaxies & The Milky Way

Question 1

Describe the shape of ellipticals, spirals, barred spirals, and irregular galaxies.

Answer 1

-Ellipticals: No spiral arms, round to elliptical shape
-Spirals: Have central bulge, halo, disk, and spiral arms
-Barred spirals: Spirals that have a bar running through their centers
-Irregular- Lower mass galaxies; often satellites of more massive galaxies

Question 2

What is the hubble fork?

Answer 2

The classification scheme for galaxies according to shape, prominence of spiral arms, and bards

Question 3

Describe the stars that would be in a spiral galaxy.

Answer 3

-Bluer
-Younger
-Bigger
-Forming new stars

Question 4

Describe the stars that would be in a elliptical galaxy.

Answer 4

-Redder
-Older
-Smaller
-Less likely to form new stars

Question 5

What happens when disk galaxies merge?

Answer 5

The stellar orbits get mixed up and the result is likely more elliptical

Question 6

What are two things that older galaxies have?

Answer 6

-They’ve had more time to merge with other galaxies
-Used up most of their gas

Question 7

Describe the properties of the Milky Way’s disk

Answer 7

-The disk is very thin (~100,000 ly wide and 2,000 ly thick)
-Almost all young stars are found in the disk within 100 ly of the plane

Question 8

What happens to stars within 10,000 ly from the Milky Way’s galactic center?

Answer 8

They aren’t confined to the disk and bulge outward

Question 9

What are dark matter halos?

Answer 9

Big, diffuse blobs of dark matter that surround galaxies that are often spherical in shape

Question 10

What type of galaxy is the Milky Way?

Answer 10

Spiral