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PHY S 100 > Units 32-33 > Flashcards

Units 32-33 Flashcards

1
Q

Galaxy

A

A large collection of stars, dust, and gas that is found in a wide variety of sizes ranging from a few million solar masses for a small galaxy to large galaxies with more than a trillion solar masses of material.

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2
Q

Radar ranging

A

A technique for measuring distance where pulses of microwaves (radar) traveling at the speed of light are sent to a nearby object and the reflected pulse is timed in order to determine the distance.

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3
Q

Laser Ranging

A

A technique for measuring distance similar to radar ranging, but instead of reflecting microwaves, laser light is reflected off a nearby surface and the time for the reflected pulse is observed.

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4
Q

True or False: Radar ranging is limited to our solar system

A

True

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5
Q

Why is radar ranging too weak for measuring distances to stars?

A

Because it’s an echo of microwaves. The echo is too weak on the return to be detected at much farther distances

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6
Q

What method is used to find the distance to stars?

A

Triangulation

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7
Q

Triangulation

A

A distance measuring technique that involves observing the angle to a distant object from at least two different locations with a known separation. Then you determine the unknown by comparing the observed angles.

Basic trigonometry.

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8
Q

True or False: According to the triangulation method’s calculations, a larger shift in angle means the object is closer

A

True

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9
Q

Light year

A

The distance light travels in a year. About ten trillion kilometers

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10
Q

Distance ladder

A

A method used in astronomy where greater and greater distances are determined using many different measuring techniques that overlap to establish a sequence of increasing distances.

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11
Q

What is the brightness distance technique?

A

Estimate the diameter of a star and look at its labels to determine how far away it is. Based on the brightness we can observe.

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12
Q

True or False: Brightness distance technique used for far away objects within 100 galaxies of earth

A

True

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13
Q

Doppler shift

A

The change in the frequency of a wave when the source and the observer are moving relative to each other.

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14
Q

Terrestrial planets

A

The rocky planets Mercury, Venus, Earth, and Mars

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15
Q

Jovian planets

A

Giant gas planets Jupiter, Saturn, Uranus, and Neptune

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16
Q

What does color tell us?

A

What the planets’ chemical composition is

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17
Q

What did the IAU (international astronomical union) determine were the qualifications of being a “planet”?

A
  1. Orbits the sun
  2. Has sufficient mass for its self-gravity to overcome rigid body forces in order to assume a nearly round shape
  3. Has cleared the neighborhood around its orbital path (pluto hasn’t done that yet)
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18
Q

True or False: Reflecting light through the gases of jovian planets helps us understand their chemical composition

A

True

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19
Q

Nebular hypothesis

A

The idea that the sun, the planets, and other objects in the solar system all formed from a single gigantic cloud of gas and dust. This hypothesis explains the major features and structure of the solar system.

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20
Q

True or False: The Jovian planets likely have metallic cores (liquid or solid)

A

true

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21
Q
A
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22
Q

What does “dust” mean in astronomical terms?

A

The metals and everything that is solid in the cold of space

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23
Q

Why is the center of the solar system so hot?

A

Because of all the kinetic energy from objects being pulled to the densest part of the solar system (gravitational potential energy causes kinetic)

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24
Q

Why is the solar system on a plane?

A

Because of the law of conservation of angular momentum. The cloud flattened out into a disk of rotating gas and dust being pulled inward.

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25
Q

When the solar system is pulled inward, does it move faster or slower?

A

Faster (angular momentum)

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26
Q

What is “accretion”?

A

Gas molecules bouncing off each other while dust sticks together forming larger and larger collections.

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27
Q

What is a protoplanet?

A

When the dust molecules accumulated so much that their diameter was more than a few kilometers. Then gravity becomes more important than random collisions

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28
Q

Why are the Jovian planets larger than the terrestrial planets?

A

Because there was more ice material in the solar system than metals

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29
Q

Lunar highland

A

The old, heavily cratered terrain on the moon that is thought to contain material from the original lunar surface.

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30
Q

Maria

A

The large, generally crater-free lava plains commonly found on the side of our moon that faces Earth (singular: mare).

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31
Q

What speed does radar ranging travel at?

A

Speed of light

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32
Q

Do stars that are farther away or closer have small angles when using the triangulation method?

A

Farther away

33
Q

On what step of the distance ladder is parallax?

A

It’s with triangulation

34
Q

What does a red shift mean?

A

It applies to absorption lines. It means the object is moving farther away from the earth

35
Q

How do we know the masses of planets outside of earth?

A
  1. We know the gravitational acceleration, we do THIS by #2.
  2. An orbiting object is falling. By measuring the orbit of ANY orbiting object, we know the gravitational acceleration.
36
Q

True or False: Astronauts “float” because they are falling

A

True

37
Q

Which formed first on the moon, the lunar highland or Maria?

A

lunar highland

38
Q

Why do clouds or anything spinning in 3D space eventually flatten into disks?

A

Because the upwards and downwards forces cancel out when the atoms/molecules/things crash into each other.

39
Q

Why do all the planets spin in the same direction?

A

Because they were all formed from the same nebular cloud which spun in the same direction.

40
Q

True or False: Gases have a hard time sticking together

A

True

41
Q

What are the three fundamental interactions that determine how stars behave?

A
  1. Gravity
  2. EG
  3. Strong nuclear
42
Q

Interstellar medium

A

Gas and dust found in the space between stars

43
Q

Molecular cloud

A

A cold cloud of dust and gas dense enough to form stars. Sometimes billions of times denser than the typical interstellar medium

44
Q

What two forces determine the current state of the star in its life cycle?

A

The balance between the EG and gravity

45
Q

Protostar

A

An object that will become a star in the early stages of formation before it begins to produce energy from fusion.

A planet before there is technically a fully functioning “star”

46
Q

True or False: The most massive stars are created more quickly than smaller stars

A

True

47
Q

Brown dwarf

A

A low mass that is too small to sustain fusion reactions in its core

48
Q

Main sequence

A

This describes stars in the longest lasting stage of their life, where hydrogen fusion is happening in the core

49
Q

Photosphere

A

The visible surface of our sun or stars. The region where visible energy is radiated into space.

50
Q

When does a protostar become a star?

A

When fusion becomes the energy source, instead of gravitational potential energy

51
Q

What is the “adult” phase of a star formation?

A

Main sequence

52
Q

What color are the coldest stars?

A

Red

53
Q

What color are the hottest stars?

A

Blue

54
Q

True or False: The hottest stars are most likely to be the most massive

A

True

55
Q

True or False: Hottest stars (with high fusion rates) have the youngest lives

A

True

56
Q

Red giants

A

A large, bright, cool star that has exhausted most of the hydrogen fuel in its core

57
Q

Planetary Nebula

A

A glowing shell of gas that has been blown off a red giant star.

58
Q

White dwarf

A

A small star that no longer sustains nuclear fusion and has shrunk to become a dense object about the size of earth

59
Q

True or False: White dwarfs are very dense

A

True

60
Q

True or False: Our sun can turn into a red giant and then into a white dwarf

A

True

61
Q

Black dwarf

A

The remains of a sun-sized star that have evolved to a white dwarf and subsequently cooled to where it no longer emits light.

A dead star

62
Q

Supernova

A

A rare celestial phenomenon involving the explosion of most of the material in a star, resulting in an extremely bright, short lived burst of energy.

63
Q

Neutron star

A

The remnant of a supernova explosion that is composed almost totally of neutrons. It is so dense that the entire mass of our Sun could be contained in a sphere only a few tens of kilometers in diameter.

64
Q

Pulsar

A

A variable radio source that is thought to be a rapidly rotating neutron star.

65
Q

True or False: It is believed that all elements heavier than iron are produced in supernova explosions

A

True

66
Q

Black hole

A

Any object where gravity is so strong that not even light can escape from its surface

67
Q

Luminosity

A

The rate at which energy is radiated from an object

68
Q

Apparent brightness

A

How bright a star appears to an observer on Earth. It is a measure of the absolute luminosity as affected by distance from the object.

69
Q

Absolute luminosity

A

The actual amount of energy radiated from an object

70
Q

H-R Diagram

A

A plot of stellar absolute luminosity verses color. Stars fusing hydrogen to helium in their cores lie along the main sequence in these diagrams

71
Q

Cepheid Variable

A

A pulsating star used to find distances. It has a well known relation between its pulsation period and absolute luminosity

72
Q

Apparent brightness

A

How bright a star appears to an observer on Earth. It is a measure of the absolute luminosity of the star as affected by the distance from the star to Earth.

73
Q

Hydrogen burning

A

Hydrogen fusing to helium.

74
Q

Main sequence

A

(1) Position on the H-R diagram where the majority of the stars fall; (2) stage of a star in which hydrogen fusion is occurring in the core of the star.

75
Q

Pulsar

A

A radio source that is thought to be a rapidly spinning neutron star.

76
Q

Type 1A Supernova

A

A type of supernova whose maximum brightness is always the same. It is, therefore, useful in determining distances.

77
Q

Supernova remnant

A

A glowing shell of gas that was ejected from a supernova as well as the interstellar material that is swept up by this expanding shell of gas.

78
Q
A

PHY S 100 (18 decks)

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