The Milky Way & Dark Matter

Question 1

What are the Three Main Structures of the Milky Way?

Answer 1

Disk, Halo, Bulge

Question 2

What is the Milky Way Comprised of?

Answer 2

Disk: Nebulae, Open Clusters (stars loosely held together by gravity), Individual Stars

Halo: Globular Clusters (spherical center full of stars), Satellite Dwarf Galaxies (smaller galaxies with stars that orbit their own center that orbit a larger galaxy)

Bulge: Central concentration full of stars

Question 3

Halo Structure

Answer 3

A spherical-like shape that surrounds the Disk & Bulge

Question 4

Spiral Arms

Answer 4

Flat, rotating disks containing stars, gas, and dust with a bulge center.

Density Waves; compression waves that caused pile-up of stars and gas at crest.

Question 5

Geometry of Milky Way Structures

Answer 5

Warped Disk; indicates collision between other galaxy.

Squished Bulge

Question 6

Dark Matter

Answer 6

Comprised of particles that do not absorb, reflect, or emit light

Question 7

How is Dark matter measured?

Answer 7

Comparing visible mass to actual mass.

Visible Mass - Stars, Gas, & Dust
Actual Mass - Motions or Curved Spacetime

Question 8

How are Galaxies measured?

Answer 8

Measuring motions. Measuring motions infer where mass is. (KEPLER’S THIRD LAW)

Question 9

What did Vera Rubin do?

Answer 9

Measured rotation curves of galaxies and found discrepancy between prediction motion of galaxies and observed motion of galaxies.

Proved that matter is spread out evenly, not centric (core had high concentration of visible stars in center) which established presence of Dark Matter.

Question 10

Draw the Structure of the Milky Way

Answer 10

!

Question 11

What is the distance of the Milky Way?

Answer 11

100,000 light years