Final

Question 1

An astronaut who fell into a black hole would be stretched because,

Answer 1

the force of gravity increases quickly over short distances.

Question 2

If the Sun collapsed to a black hole today, how would it affect the Earth?

Answer 2

It would be dark

no effect on orbit and nobody would be ‘sucked’ off Earth

Question 3

The formation of the Milky Way’s ______ depended on the presence of gas.

Answer 3

disk

Question 4

Halo objects orbit the center of the Milky Way

Answer 4

in random orientations and directions

Question 5

The Milky Way’s ______ composed of stars (and gas and dust) in randomly oriented orbits.

Answer 5

halo and bulge are

Question 6

Most of the mass in the Milky Way is,

Answer 6

dark matter

Question 7

A DVD’s rotation curve (velocity vs. radius) graph,

Answer 7

increases as radius increases

Question 8

A disk galaxy’s rotation curve,

Answer 8

is relatively constant as radius increases.

Question 9

The Milky Way’s rotation curve provides evidence of dark matter because

Answer 9

• additional, invisible matter is required to keep the rotation speed relatively constant.
• the rotation curve extends far beyond the Milky Way’s disk

Question 10

You’ve found a dwarf galaxy that may be orbiting the Andromeda Galaxy. Refer back to your text to determine which of the following steps on the distance ladder could be used to determine its distance, assuming it is nearby Andromeda. (check all that apply

Answer 10

• White dwarf (Type 1a supernova)

- cepheid variable star

Question 11

Which object can not be used to measure distances?

Answer 11

A massive star (type II) supernova

Question 12

An astronomer has found an object in a distant galaxy that appeared suddenly, grew in brightness for a short time, and then faded from view. The light curve of this object can be used to determine,

Answer 12

what kind of object it is, and if it can used to measure distance at all.

Question 13

An observer at a UW observatory detects a white-dwarf supernova in a distant galaxy right now. An observer looking at the same location right now from inside that distant galaxy, could observe,

Answer 13

supernova remnant, but nothing else.

Question 14

Imagine three widely separated galaxies arranged in a line. If you are in the first galaxy (galaxy number 1) you observe that both the middle (number 2) and the right (number 3) galaxies are moving away from you.

If you asked observers in galaxy number 3 how galaxy number 2 appeared to move, what would they say?

Answer 14

Galaxy 2 is moving away from Galaxy 3

Question 15

Astronomers observe two galaxies, A and B. Galaxy A has a recessional velocity of 1000 km/s, while galaxy B has a recessional velocity of 2000 km/s. This means that:

Answer 15

Galaxy B is twice as far away as galaxy A.

Question 16

A star that is moving toward us will have,

Answer 16

its spectral lines shifted to shorter wavelengths.

Question 17

Which is likely to have the largest redshift?

Answer 17

a galaxy (not a star)

Question 18

Which type of galaxies appear to have many young stars?

Answer 18

disk galaxies

Question 19

Do the disk galaxies also contain old stars?

Answer 19

yes

Question 20

Which type of galaxies are more likely to show evidence of dust?

Answer 20

disk galaxies

Question 21

If a galaxy is experiencing active star formation, it must contain

Answer 21

cool, dense gas

Question 22

Which type of galaxies have cool, dense gas available for star formation?

Answer 22

disk galaxies

Question 23

Which type of galaxy shows evidence of significant numbers of O-stars and M-stars?

Answer 23

disk galaxies

Question 24

Which type of galaxy is likely to contain many M-stars but few O-stars?

Answer 24

elliptical galaxies

Question 25

Consider the discussion among three students about a galaxy that appears red

Answer 25

it’s just that blue stars don’t last very long. -the blue stars that may have been there in the past have already evolved into red giants, so the galaxy looks red due to the light from all the red giants

Question 26

velocity equation

Answer 26

v = cz ``` z = redshift c = speed of light (3.0 x 10^5 km/sec) ```

Question 27

Galaxy vs star redshifts

Answer 27

Galaxies have much larger redshifts than stars

Question 28

Spectral lines of galaxies redshift

Answer 28

shifted toward longer wavelengths | = moving away from us

Question 29

Observations of which of the following objects revealed the accelerated expansion of the universe?

Answer 29

supernovae

Question 30

It has been shown from recent observations that the universe is not only expanding but that the expansion is accelerating! Which of the following is believed to be responsible for the acceleration?

Answer 30

dark energy

Question 31

Over time the universe has become

Answer 31

bigger, cooler, and less dense

Question 32

Which of the following are moving apart due to the expansion of the universe?

Answer 32

two widely separated galaxies

Question 33

How is the motion of galaxies in our local group different from what we observe for distant galaxies?

Answer 33

some are moving toward us

Question 34

The center of the Universe:

Answer 34

may not even exist

Question 35

Why aren't the Milky Way, the Solar System, and even the Earth ripped apart due to the expansion of the Universe?

Answer 35

The expansion of the Universe only occurs on the largest scales, and can only carry apart objects that aren't bound to each other.

Question 36

Observations of the Cosmic Microwave Background Radiation have given us the following current composition of the universe: 5% Normal Matter, 23% Dark Matter, and 72% Dark Energy. How was the composition of the early universe different?

Answer 36

there was less dark energy

Question 37

Which of the following will determine if the universe will expand forever?

Answer 37

- The amount of dark matter in the universe. - The amount of dark energy in the universe. - The amount of normal matter in the universe.

Question 38

Astronomers measure a star's color by,

Answer 38

comparing its brightness through two different filters.

Question 39

Consider the following four stars, their g magnitudes, and their g-r colors: ``` Star g g-r A 12. -0.4 B 15. 1.3 C 14. 1.2 D 16. 0.2 ``` Which is brightest in the sky?

Answer 39

A

Question 40

Consider the following four stars, their g magnitudes, and their g-r colors: ``` Star g g-r A 12 -0.4 B 15 1.3 C 14 1.2 D 16 0.2 ``` Which is bluest?

Answer 40

A

Question 41

Consider the following four stars, their g magnitudes, and their g-r colors: ``` Star g g-r A 12 -0.4 B 15 1.3 C 14 1.2 D 16 0.2 ``` Which is the least luminous?

Answer 41

need more information to tell

Question 42

The horizontal axis of a spectrum in astronomy is,

Answer 42

wavelength