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Astronomy > Units 3 & 4 > Flashcards

Units 3 & 4 Flashcards

1
Q

A high-luminosity star…

A

emits more light than a low-luminosity star.

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2
Q

If a red giant appears the same brightness as a red main sequence star, which one is farther away?

A

the red giant

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3
Q

The heaviest nucleus of all formed…

A

during a supernova explosion

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4
Q

Hydrogen-2 + proton = ______ + energy

A

Helium-3

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5
Q

Which of the following has the smallest radius?
A: type A main sequence star
B: main sequence star with surface temperature 8000 K
C: type K main sequence star
D: white dwarf
E: neutron star

A

E: neutron star

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6
Q

Why does the main sequence part of a star’s life end?

A

The Hydrogen in the core is exhausted.

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7
Q

Which of the following will have the shortest lifetime on the main sequence?
A: main sequence star with surface temperature 20000 K
B: main sequence star with surface temperature 3000 K
C: main sequence star with luminosity one tenth that of the Sun
D: the Sun
E: main sequence star with mass 2 times the Sun’s

A

A: main sequence star with surface temperature 20000 K

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8
Q

Many of the brightest 100 stars viewed from Earth are not on the main sequence
(even though most stars are) because …

A

the most luminous stars are giants and supergiants that have already
finished their main sequence lifetimes.

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9
Q

A 2-solar-mass main sequence star is at the same distance as a 0.2-solar-mass main
sequence star. Which star appears brighter?

A

the 2 solar mass main sequence star appears brighter

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10
Q

The temperature of the photosphere of the Sun is closest to …

A

6000 kelvin

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11
Q

An estimate of the number of communicating / technological civilizations that we
expect in our Galaxy would be a larger number if …

A

the average number of planets that could support life for each star were larger

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12
Q

If the Sun had twice its mass, then which of these planets would be in its habitable
zone?

A

Jupiter

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13
Q

COME BACK TO 13!!!

A
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14
Q

How do astronomers measure the temperature of stars?

A

By looking at which absorption lines are present in the star’s spectrum.

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15
Q

COME BACK TO 15!!!

A
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16
Q

The largest fraction of nearby stars (e.g., within 100 light years) are …

A

red main sequence stars

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17
Q

COME BACK TO 17!!!

A
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18
Q

COME BACK TO 18!!!

A
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19
Q

The parallax angle of a nearby star is measured to be 0.02 arcseconds. What is the
distance to the star?

A

50 parsecs

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20
Q

What is the sequence of events for a 40-solar mass star
(one of the most-massive stars)?

A

stellar nursery, protostar, blue star on main sequence, Type II supernova,
black hole

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21
Q

Star A is 9 times as luminous as Star B. The two stars appear the same brightness.
What is true about their distances?

A

Star A is 3 times farther away than Star B.

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22
Q

COME BACK TO 22!!!

A
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23
Q

What is the name of the slightly cooler layer of the Sun just outside the
photosphere?

A

Chromosphere

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24
Q

How does a star move on the H-R diagram during the period of time it is converting
hydrogen to helium in its core?

A

It remains nearly fixed at a certain point on the main sequence and does
not move on the H-R diagram.

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25
Q

If the entire mass of Earth were concentrated in a region the size of a marble, the
resulting object would be …

A

A black hole

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26
Q

What is the smallest object?

A

A neutron star

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27
Q

A galaxy has an H-alpha emission line observed at a wavelength 10 percent larger
than the rest wavelength of H-alpha. What is the redshift of the galaxy?

A

0.1

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28
Q

COME BACK TO 28!!!

A
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29
Q

Which is the most luminous?
A: nova
B: supernova
C: quasar
D: the Sun
E: white dwarf

A

C: quasar

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30
Q

Which contains the most stars?
A: an open star cluster
B: a globular star cluster
C: a spiral galaxy
D: the Solar System
E: the alpha Centauri star system

A

C: a spiral galaxy

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31
Q

Galaxy A appears twice the angular size of Galaxy B. Assuming the two galaxies
have the same physical size in kiloparsecs, which of the following is true?
A: Galaxy A is 2 times farther away than Galaxy
B: Galaxy B is 2 times farther away than Galaxy
C: Galaxy A and B are at the same distance.
D: Galaxy A is 4 times farther away than Galaxy
E: Galaxy B is 4 times farther away than Galaxy

A

B: Galaxy B is 2 times farther away than Galaxy

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32
Q

What fundamental particles make up a Helium-3 atom?

A

5 up quarks, 4 down quarks, 2 electrons

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33
Q

COME BACK TO 33!!!

A
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34
Q

Which statement is FALSE?
A: planetary nebulae can have layers because of pulsating stars
B: planetary nebulae usually last tens of thousands of years
C: a planetary nebula will be part of the end state of the Sun
D: planetary nebulae usually have black holes at their centers
E: planetary nebulae are a few light years in size

A

D: planetary nebulae usually have black holes at their centers

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35
Q

Which statement is TRUE?
A: Stars form in molecular clouds, where temperatures are about 10 Kelvin.
B: A cloud will collapse and form stars if its mass is a lot less than its Jeans mass.
C: A nova outburst typically only happens once in a star’s life.
D: Stars usually form in isolation, far away from other stars
E: The Crab supernova, in our galaxy, went off about 8 years ago

A

A: Stars form in molecular clouds, where temperatures are about 10 Kelvin.

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36
Q

How tiny a spot is the Hubble Deep Field?

A

The size of President Roosevelt’s eye on a dime held at arm’s length.

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37
Q

Among these choices, what is the last thing that happens in the history of the Universe?
A: electrons join with nuclei to make atoms
B: quarks join together to make protons and neutrons
C: nucleosynthesis
D: the Planck epoch
E: the Big Bang expansion begins

A

A: electrons join with nuclei to make atoms

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38
Q

If a galaxy had no dark matter, we would observe …

A

the rotation velocity would decrease with increasing distance like the
Keplerian curve in our Solar System

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39
Q

How many times bigger is the Local Group of galaxies in which the Milky Way
resides than the Milky Way itself?

A

about 100 times bigger

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40
Q

Which one of the following is FALSE?
A: Irregular galaxies, although small, often have a lot of star formation taking
place in them.
B: Barred spiral galaxies have similar properties to normal spirals, except for
the “bar” feature.
C: Galaxy collisions destroy most of the stars in the galaxies involved.
D: Most galaxies appear to be receding from the Milky Way Galaxy.
E: Most elliptical galaxies contain only old stars.

A

C: Galaxy collisions destroy most of the stars in the galaxies involved.

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41
Q

If a galaxy is moving away from us the wavelength of the light it emits will be …

A

increased.

42
Q

The stars in the halo of our Milky Way Galaxy are …

A

older and redder than those in the disk.

43
Q

The supermassive black hole in the center of the Milky Way has a mass of …

A

4 million solar masses

44
Q

COME BACK TO 44!!!

A
45
Q

Which force has the photon as its boson?

A

electromagnetic

46
Q

Which mysterious phenomena do scientists attribute to dark energy?

A

The increasing rate of expansion of the Universe.

47
Q

Why can we NOT see back the whole way to the time Big Bang expansion began?

A

The radiation scatters off matter frequently so the Universe is opaque.

48
Q

What are the “standard candles” that were used to determine the Universe is
accelerating?

A

Type Ia supernovae

49
Q

An older star cluster …

A

has a main sequence turnoff farther to the right on the H-R diagram.

50
Q

Which of the following statements is TRUE?
A: One or two supernova are observed to go off in the Milky Way galaxy
each year.
B: Type II supernovae are produced by the death of a massive star.
C: Type Ia supernovae show a lot of strong hydrogen lines in their spectra.
D: Type Ia supernovae are produced when a neutron star collapses to become a
black hole.
E: When a planetary nebula is produced it can outshine an entire galaxy.

A

B: Type II supernovae are produced by the death of a massive star.

51
Q

If the radius of Star A is twice the radius of Star B, but both have similar temperatures, how do their luminosities compare?

A

Star A is four times as luminous as Star B.

52
Q

When using different points in the Earth’s orbit as a baseline for a parallax experiment it is best to do the observations…

A

6 months apart.

53
Q

A star is stable due to the balance of…

A

gravity and gas pressure.

54
Q

Star “A” is three times farther away from the Sun than Star “B.” The parallax angle of Star “B” is…

A

three times larger than that of Star “A.”

55
Q

If a red giant appears the same brightness as a red main sequence star, which one is
farther away?

A

the red giant

56
Q

How do astronomers measure the temperature of stars?

A

By looking at which absorption lines are present in the star’s spectrum.

57
Q

COME BACK TO 7-2!!!!

A
58
Q

COME BACK TO 8-2!!!

A
59
Q

Most stars …
A: have larger radii than the Sun.
B: are red giants.
C: end their lives as black holes.
D: are more luminous than the Sun.
E: are less massive than the Sun.

A

E: are less massive than the Sun.

60
Q

After doubling the distance from a light source, a light detector collects …

A

one quarter as much light

61
Q

You measure the parallax angle of a star to be 0.05 arcseconds. How far away is it?

A

20 parsecs

62
Q

What is the first step in the p-p chain?

A

a proton combines with a proton to make Hydrogen-2 (Deuterium)

63
Q

Which of the following is the only property of a star that depends on its distance
from the observer?

A

brightness

64
Q

The most successful early planet finding mission, launched in 2009, was called …

A

Kepler

65
Q

Which of the following is TRUE?
A: life does not exist in the darkness of Earth’s seas
B: more massive stars have habitable zone farther away from them
C: K type stars can’t have planets around them
D: the habitable zone has temperatures low enough that water can freeze
E: less massive stars than the Sun are more luminous than the Sun

A

B: more massive stars have habitable zone farther away from them

66
Q

Which of the following is TRUE?
A: habitable planets have been found around red dwarfs as well as around
Sun-like stars
B: the Kepler mission has discovered many supernova explosions
C: the first planets found, in 1992, were in orbit around a G0 type main
sequence star
D: all extrasolar planets were discovered after 2001
E: planets the mass of Jupiter cannot exist at distances less than 1AU from their stars

A

A: habitable planets have been found around red dwarfs as well as around
Sun-like stars

67
Q

COME BACK TO 17-2!!!!

A
68
Q

Which is roughly the size of Earth?
A: a black hole
B: an M type main sequence star
C: a neutron star
D: a red giant
E: a white dwarf

A

E: a white dwarf

69
Q

COME BACK TO 19-2!!!

A
70
Q

Which is the hottest part of the Sun?

A

Core

71
Q

“Slurpy’s” home planet was at a distance of 0.55AU from its parent star. And it was
habitable. Because of this, we knew …

A

it was an M type star.

72
Q

COME BACK TO 22-2!!!

A
73
Q

An “onion skin” shell burning structure, with elements up to iron being produced,
develops in …

A

a star much more massive than the Sun

74
Q

If the Sun had twice its mass, then which of the planets would be in its
habitable zone?

A

Jupiter

75
Q

Which chemical element cannot be produced in the core of any star?

A

Gold

76
Q

A galaxy has an H-alpha emission line observed at a wavelength 10 percent larger
than the rest wavelength of H-alpha. What is the redshift of the galaxy?

A

0.1

77
Q

How many stars are there in the observable universe?
(based on the Hubble Deep Field Academy activity that you did)

A

10^22 stars

78
Q

Why do you suppose the Cat’s Eye Nebula has a certain symmetry?

A

Bipolar jets are creating matching shapes on both sides.

79
Q

The largest stars are almost the size of …

A

our Solar System.

80
Q

What populations of stars are relatively old?

A

Globular clusters

81
Q

What type of radiation does dark matter emit?

A

None

82
Q

COME BACK TO 32-2!!!

A
83
Q

What elements are in the Cassiopeia A supernova remnant?
A: oxygen
B: sulfur
C: hydrogen
D: nitrogen
E: all of the above

A

E: all of the above

84
Q

How many times bigger are galaxies than individual stars?

A

billions or trillions of times bigger

85
Q

How do you measure the mass of the supermassive black hole at the center of the
Milky Way?

A

look at the orbits of nearby stars and apply Kepler’s third law

85
Q

What is at the center of the Crab Nebula, that produces its magnetic field?

A

A neutron star

86
Q

How many “up” and “down” quarks make up a proton?

A

Two ups and a down

87
Q

What happens to the planets in a galaxy when that galaxy collides with
another galaxy?

A

Nothing, because the spaces between stellar systems in a galaxy is much
larger than their size.

88
Q

What is so special about Type Ia supernova that make them good distance
indicators?

A

their luminosities are known.

89
Q

What is the boson for the strong force?

A

gluon

90
Q

The redshifts of galaxies are found to be larger …

A

for galaxies that are farther away.

91
Q

True or False? The primary evidence for an accelerating universe comes
from observations of young stars in the Milky Way.

A

False; in order to measure accelerating expansion, we need to measure
the distances of objects billions of light-years away.

92
Q

The supermassive black hole in the center of the Milky Way has a mass of …

A

4 million solar masses

93
Q

COME BACK TO 44-2!!!

A
94
Q

What parameters does Hubble’s law relate to each other?

A

galaxy recession velocity and distance

95
Q

Which force has the photon as its boson?

A

electromagnetic

96
Q

How have astronomers interpreted the unexpectedly fast rotation of galaxies?

A

There must be a lot of dark matter whose gravity can be felt but not seen.

97
Q

What are the differences between open star clusters and globular star clusters?

A

open clusters are less concentrated, younger, and have fewer stars

98
Q

If light takes 4 billion years to reach us from a distant galaxy, how many times
farther away is that distant galaxy than the Andromeda galaxy, which is 2 million
light-years away?

A

2,000 times

99
Q

Which contains the most stars?
A: the Solar System
B: an open star cluster
C: a globular star cluster
D: the alpha Centauri star system
E: a spiral galaxy

A

E: a spiral galaxy

Astronomy (2 decks)

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