Astronomy Final Exam: Chapters 16 & 17

Question 1

What are elliptical galaxies?

Answer 1

Made of mostly old stars & do not have much gas or dust

Question 2

What are spiral galaxies?

Answer 2

A galaxy where the stars & gas clouds are concentrated mainly in one or more spiral arms w/ dust

Question 3

What are irregular galaxies?

Answer 3

Galaxies with no distinct shape w/ gas & dust

Question 4

What does gravitational lensing detect?

Answer 4

Dark matter

Question 5

What is gravitational lensing?

Answer 5

Light is bent causing curves in space seen through a “lens”

Question 6

What is galactic rotation?

Answer 6

The plot of orbital speeds of visible stars or gas in the galaxy versus their radial distance from that galaxy’s center

Question 7

Who identified spiral nebula as galaxies?

Answer 7

Lord Rosse

Question 8

What is Hubble’s Law?

Answer 8

Redshifts in the spectra of distant galaxies are proportional to their distance

Question 9

What is the importance of Hubble’s Law?

Answer 9

How fast the Universe is expanding is used to determine age / history

Question 10

Hubble’s Law theorized for galaxies how far away?

Answer 10

160 km / s per million light years

Question 11

Hubble’s Law explains what about galaxies?

Answer 11

A galaxy’s velocity is directly proportional to its distance

Question 12

Are Galactic Collisions common?

Answer 12

Yes

Question 13

What are star burts?

Answer 13

Collisions or near passes with other galaxies

Question 14

What are quasars?

Answer 14

Supermassive black holes feeding on gas at the center of a distant galaxy

Question 15

What do quasars create?

Answer 15

Other galaxies by accreting surrounding gas & dust

Question 16

How do black holes form?

Answer 16

Gas slowly loses energy & angular momentum causing it to move inward, speed up, & heat up

Question 17

What is the Unified Model?

Answer 17

A model of a supermassive black hole surrounded by a thick ring or rows of dust