Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Astronomy > Exam 4 > Flashcards

Exam 4 Flashcards

1
Q

Bright, sphere-shaped region of stars that occupies the central few thousand lightyears of the milky way galaxy

A

Galaxy’s Bulge

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Gas and Dust that lies between the stars in the Milky Way Galaxy

A

Interstellar medium

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Two smaller galaxies that orbit the Milky Way Galaxy

A

Magellanic clouds

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

The continuous recycling of gas in the galactic disk between stars and the interstellar medium…

A

Star-Gas-Star Cycle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is 2% of the mass of the milky ways interstellar medium?

A

Elements heavier than hydrogen and helium

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Subatomic particles that travel close to the speed of light

A

Cosmic Rays

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is the most abundant chemical in molecular clouds?

A

H2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What does interstellar dust mostly consist of?

A

Microscopic particles of carbon and silicon

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

A cloud of hydrogen and helium that contracts to become a galaxy

A

Protogalactic Galaxy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Most stars in the Milky Way Galaxy are…

A

very old

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

A colorful cloud of gas that glows because it is heated by light from nearby hot stars

A

Ionization Nebula

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Most common form of gas in the disk of the Milky Way Galaxy

A

Atomic Hydrogen Gas

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What law of nature explains why the galaxy began to rotate rapidly and flattened out as it shrunk in size?

A

Law of Conservation of Angular Momentum

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

The circular but relatively flat portion of the galaxy

A

Disk

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

First Portion of the galaxy to form

A

Halo

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

A tightly packed group of a few hundred thousand, very old stars

A

Globular Cluster

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Stands out in a photo of a galaxy because it shines brightly with light from massive young stars and glowing clouds of gas and dust

A

Spiral Arm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Stars orbiting in the _____ near the galaxy’s center can have orbits highly inclined to the galactic plane

A

Bulge

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Estimated number of galaxies in our observable universe

A

100 Billion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

NOT one of the major clusters

A

Global Clusters

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Dark energy has been hypothesized to exist in order to explain…

A

Observations of galaxies suggesting the expansion of the universe is accelerating

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Dark Matter in inferred to exist because…

A

We can observe it’s gravitational influence on visible matter

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Strong evidence for the existence of dark matter comes from the observations of…

A

Orbital Periods (rotation curve) of stars in the milky way galaxy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What is meant in cosmology by “critical density”?

A

The density that determines whether the universe expands forever or re-collapses

25
Q

Why do we think galactic collisions were more common in the past?

A

The early universe was smaller, therefore galaxies were closer to each other in the past

26
Q

What do we think lies at the center of the universe?

A

Cosmology tells us there is no center

27
Q

Which type of galaxy contains very little interstellar gas?

A

Elliptical

28
Q

What does the big bang theory predict could be seen today?

A

Radiation that is coming from all directions in space, and has been red-shifted to microwave spectrum

29
Q

Using powerful telescopes to look back in time over 10 billion years, what did we discover the most distant (youngest) galaxies to look like?

A

Very Irregular

30
Q

What is the rotation curve of a spiral galaxy?

A

A plot of the rotation (orbital) speeds of its stars vs. distance from the center of the galaxy

31
Q

{TRUE OR FALSE} When we look at the cosmic microwave background radiation, we are looking further into space (back in time) than when we loom at the farthest galaxies

A

True

32
Q

Matter fall into super-massive black holes in the centers of some galaxies is thought to be the source of:

A

Active Galactic Nuclei, Strong Radio Sources, Giant jets that shoot far into space, and Quasars

33
Q

{TRUE OR FALSE} A main goal of the Hubble Space Telescope was to measure the Hubble Constant, H0 as 1/H0 to give us the best estimate of the current age of the universe

A

True

34
Q

About how old was the universe when galaxies appeared?

A

1 Billion Years Old

35
Q

A light source of known luminosity

A

Standard Candle

36
Q

Where do we think fark matter primarily resides in our galaxy?

A

In the Halo region and it’s surroundings

37
Q

Why have astronomers recently determined that there must be an additional strong force, termed “dark energy” acting on the universe?

A

They have measured an unexpected acceleration in the expansion

38
Q

{TRUE OR FALSE} The existence of dark matter has been established by observing it with specialized dark matter telescopes

A

False

39
Q

What is currently believed to make up the majority of dark matter?

A

WIMPS

40
Q

About what age is the universe?

A

14 Billion Years Old

41
Q

What TWO things happen when galaxies collide?

A

Strong gravitational forces will distort the shape of the galaxy and Molecular gas clouds will collapse. creating star bursts that enhance star formation

42
Q

Cosmological red-shift that all distant galaxies exhibit is result of…

A

The expansion of the Universe

43
Q

{TRUE OR FALSE} The sun is a bulge star, born near the center of the galaxy

A

False

44
Q

What do we mean when we talk about the “expansion of the universe”?

A

That space itself is expanding

45
Q

{TRUE OR FLASE} Starburst galaxies have been forming stars at the same furious pace since the universe was about a billion years old

A

False- Bursts of star formation would use up all the gas in a galaxy in a much shorter period of time than the age of the universe

46
Q

What holds the Local Group of galaxies together?

A

The gravitational force

47
Q

The luminosity of a Quasar is generated in a region about the radial size of…

A

Our solar system

48
Q

How long does light from the neatest star (not including the sun) take to reach us?

A

About 4 years

49
Q

What doe we think lies at the center of the Milky Way?

A

A massive black hole

50
Q

How did Edwin Hubble first prove that the strange looking spiral nebulae were really distant galaxies?

A

He used bright Cepheid variables in them to measure their distances

51
Q

When we look at a very distant galaxy, billions of light years away, we see it…

A

When it was younger than now

52
Q

How long does it take for light to cross the milky way?

A

Around 100,000 years

53
Q

Where are most of the milky ways globular clusters found?

A

In the halo

54
Q

Where would you be most likely to find an ionization nebula?

A

In the disc

55
Q

The orbits of halo and bulge stars are special because…

A

Their orbits are randomly inclined to the disk of the galaxy

56
Q

Currently, where are stars born in the Milky Way?

A

Density waves in the disc spiral arms

57
Q

Which form of radiation passes most easily through the disk of the Milky Way?

A

Infrared Light

58
Q

How many stars do we think there are in our Milky Way Galaxy?

A

100 Billion

59
Q

Why do disc stars bob up and down as they orbit the galaxy?

A

Because the gravity of other disc stars pull them towards the disc

Astronomy (4 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions