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Astronomy > Astronomy Final > Flashcards

Astronomy Final Flashcards

1
Q

By exchanging the eyepiece in a telescope with one having a longer focal length, you are _____ the ______ power

A

decreasing; light gathering

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2
Q

what advantages is the jwst telescope’s mirror (larger and hexagonal) going to have compared to the HST (small and round)

A

an increase in light gathering power and better resolving power

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3
Q

true or false: the sun radiates most of its light as visible electromagnetic radiation

A

true

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4
Q

true or false: the doppler effect can change the wavelength of electromagnetic radiation

A

true

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5
Q

true or false: electromagnetic radiation behaves like both a wave and a particle

A

true

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6
Q

true or false: longer wavelength electromagnetic waves have more energy per photon

A

false

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7
Q

true or false: all form of EM radiation travel at the same speed in a vaccuum

A

true

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8
Q

what number expressed in powers of 10 notation with different units, best represents the distance to a nearby star (not the sun)

A

10^1 lightyear

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9
Q

study page 2 of test 1

A

got it

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10
Q

the astronomical unit (AU) is defined as the average distance between the earth and the sun. it’s value is 1.5E8 km. Saturn orbits the sun at approximately 10 AU. what number best describes this distance in km (in notations of ten)

A

10^9 km

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11
Q

how long does it take for light to travel from the earth to the moon about 300,000 km away?

A

about a second

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12
Q

Imagine that you are the head of a funding agency that can afford to build only one telescope. what telescope would be best to support

A

a gamma ray telescope in orbit above earth

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13
Q

what has the lowest frequency

A

a radio wave

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14
Q

a cloud of warm hydrogen gas is moving toward earth. what best completes the following statement describing the spectrum of this cloud?

A(n) _______ spectrum that is ______ relative to a stationary gas cloud

A

emission; blueshifted

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15
Q

gamma ray, xray, ultraviolet, visible, infrared, microwave, radio

the phrase above has values increasing to the right. what parameter could this number line represent?

A

wavelength only

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16
Q

Sirius, the brightest star in the night sky, is about 9 light-years away. if the speed of light were half of its present value, what would the distance of Sirius be?

A

18 light years.

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17
Q

study questions 14 and 15 in exam 1

A

gotcha

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18
Q

study questions 18 through 20 on exam 1

A

ok

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19
Q

how do you determine whether or not a black body spectra of two objects have the same temperature?

A

they have the same peak and same end location (y axis)

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20
Q

how do you determine size on a black body spectra of two objects?

A

wavelength

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21
Q

how do refracting telescopes collect light?

A

lenses

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22
Q

how do reflecting telescopes collect light?

A

mirrors

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23
Q

what type of most large astronomical telescopes today?

A

reflecting

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24
Q

why do we want light gathering power in telescopes?

A

the more lgp there is, the better the image will look

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25
Q

why do we want resolving power in telescopes?

A

the smaller the resolving power, the better the image

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26
Q

why do we want to build bigger telescopes? (light gathering power)

A

the bigger the distance from end to end of the telescopes mirror, the larger the lgp, thus getting a better image (LGP = Distance squared

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27
Q

why do we want to build bigger telescopes? (resolving power)

A

the bigger the distance from end to end of the telescopes mirror, the smaller the resolving power, thus getting a better image (RP = wavelength/distance)

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28
Q

how much greater is the lgp of a 6 meter telescope compared to a 3 meter telescope?

A

4 times better

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29
Q

on an energy level diagram, how is absorption with the least energy shown

A

shortest arrow going up

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30
Q

on an energy level diagram, how is emission with the shortest wavelength shown

A

longest arrow going down

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31
Q

study question 28 on exam 1

A

okie dokie

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32
Q

the description of “produced by typical stars” most appropriately belongs to which of the different types of spectra

A

absorption

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33
Q

the description of “produced by a red-colored light sign” most appropriately belongs to which of the different types of spectra

A

emission

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34
Q

the description of “not all wavelengths present” most appropriately belongs to which of the different types of spectra

A

absorption and emission

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35
Q

what is the primary reason as to why some telescopes are placed in space above earths atmosphere

A

some of the light from extraterrestrial sources is absorbed by earths atmosphere

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36
Q

rank the distances from nearest to farthest from earth

A

jupiter, the closest star other than the sun, the center of the milky way, the closest galaxy, the closest galaxy cluster.

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37
Q

when would we see a star that is neither redshifted nor blueshifted?

A

when the star is moving parallel to the observer

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38
Q

which portions of wavelength best represents reflected sunlight?

A

blue green and red

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39
Q

what does the peak of the wavelength tell us about the spectrum

A

temperature

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40
Q

what feature of a spectrum indicate the color of it,

A

the peak of intensity

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41
Q

What is light pollution

A

the lights that civilization gives off “pollutes” the vision of the night sky, making the stars not as easily seen

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42
Q

what is a solution to light pollution?

A

setting up at a remote location away from the lights of civilization such as on a mountain top or a desert

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43
Q

what is atmospheric turbulence

A

the atmosphere deflects some of the light given by stars and thus blurs the looks of them

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44
Q

what is a solution to Atmospheric turbulence

A

setting up in regions with calm atmospheric flow, such as the coastline. they also use adaptive optics

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45
Q

Barnard’s star is a main sequence star with M2 spectral type. As a result, what is always true about this star

A

it will live longer than a class B spectral type main sequence star

46
Q

what is a solution for atmospheric absorption

A

set up on a higher and drier locations such as on a mountaintop or in space

47
Q

what is always true about two stars that share the same absolute maganitude

A

they have the same luminosity

48
Q

a star has an apparent magnitude of -1.0 and an absolute magnitude of +3.0. if it were moved 10 times further away from earth as it is now, what could happen?

A

it’s apparent magnitude number would increase (get bigger)

49
Q

a star has an apparent magnitude of -1.0 and an absolute magnitude of +3.0. if it were moved 10 times further away from earth as it is now, what could happen?

A

it’s apparent magnitude number would increase (get bigger)

50
Q

star A is an M spectral type star that is 1000 times more luminous than the Sun. Star B has the same absolute magnitude as the sun and belongs to spectral type G. which star has the greatest surface temperature?

A

star A

51
Q

how do you find the parallax of a star

A

1/distance

52
Q

compared to the sun’s photosphere, the corona is:

A

higher in temperature and less dense

53
Q

Alpha Centauri A is a G2 V star at distance of 1.5 parsecs and an apparent magnitude of 0.0. what is the most likely value for the absolute magnitude

A

-4.4

54
Q

study questions 15-22 in exam 2 hard

A

got it

55
Q

study questions 10-14 in exam 2

A

alright

56
Q

study questions 10-14 in exam 2

A

alright

57
Q

how are you going to get a lot of white dwarfs

A

if you have a lot of hot young blue stars

58
Q

how do you determine a cluster’s age on an HR diagram

A

by looking at where the cluster branches off (the lower, the older)

59
Q

study questions 23-25 on exam 2

A

got’em

60
Q

during the process of star formation, which force dominates the collapse of a cloud of gas and dust?

A

gravitational force

61
Q

what is the range of the spectral types

A

OBAFGKM (oh boy a fine girl kiss me) (hottest to coolest)

62
Q

what causes sunspots?

A

concentrations of magnetic fields that reduce the surface temperature of a region of the star

63
Q

you should suspect that a dense molecular cloud has a protostar forming inside of it. which type of telescope would be the best to confirm your suspicion

A

an infrared telescope

64
Q

what is the evolutionary path for a star like our sun?

A

main sequence star, giant star, planetary nebula, white dwarf

65
Q

imagine observing a cluster where the main sequence stars with the same spectral type as our sun have apparent magnitudes of +8.0. if the absolute magnitude of the sun is +4.4, what can you say about the cluster’s distance?

A

it’s more than 10 parsecs

66
Q

Star A has a mass of 4 solar masses, and star B has a mass of 8 solar masses. how will the fusion rates, lifetimes, and luminosities of Star A and Star B compare when they are on the main sequence

A

Star A will have a lower fusion rate, lower luminosity, and a longer lifetime than star B

67
Q

x-ray images of the sun generally reveal the nature and structure of which of the sun’s layers?

A

the corona

68
Q

the parallax angle of the bright star in the Vega is approximately 0.13”. how would this angle change is vega were moved to a distance 10 times as far from earth as it is now?

A

it would get smaller

69
Q 
which of the following stars would have the largest radius:
A. A0 I
B. O7 V
C. K5 III
D. M1 I
E. M5 V
A

D. M1 I

70
Q

what is the significance of the roman numerals of spectral types?

A

size from largest to smallest (I being supergiant stars and V being main sequence stars

71
Q

what is the order of the numeral sizes

A 
I supergiant
II Asymptotic giants and horizontal branch
III red giant
IV subgiant
V main sequence
72
Q

what is the most massive nuclei that can be fused in the core of a 1 solar mass star

A

helium

73
Q

what type of stars are most common in a newly formed star cluster

A

M type main sequence stars

74
Q

what does a type 2 supernova leave behind?

A

either a black hole or a neutron star

75
Q

What is the list of methods for determining distance in the correct order from nearest to farthest

A

parallax, spectroscopic parallax, Cepheid variables, white dwarf supernova, Hubble’s law

76
Q

what is the formula for Hubble’s constant

A

Ho = v/d (recessional velocity divided by distance in megaparsecs)

77
Q

imagine you discover two white dwarfs in orbit around each other in a binary system your observations reveal that they have the same temperature but one is 10x more luminous than its companion. what is the correct explanation for your observations

A

the more luminous white dwarf is less massive than its companion

78
Q

what is the relationship between size and mass in white dwarfs

A

the more massive a white dwarf is, the smaller the star is

79
Q

what is the max mass a white dwarf can have

A

1.4 Msun

80
Q

why can Cepheid variable stars can be used as standard candles for determining distances to galaxies

A

they show a distinct, linear correlation between their pulsation periods and their luminosities

81
Q

the bulges of spiral galaxies often appear reddish in color because they contain what?

A

numerous cool, old, faint red stars

82
Q

imagine you can travel at the speed of light. Approximately how long would it take you to transverse the full diameter of the milky way’s disk

A

100,000 years

83
Q

the characteristic of “lots of gas and dust” most appropriately belongs in which position of the galaxy

A

disk

84
Q

the characteristic of “many globular clusters” most appropriately belongs in which position of the galaxy

A

halo

85
Q

the characteristic of “contains faint cool red stars” most appropriately belongs in which position of the galaxy

A

disk, bulge, and halo ( all three parts)

86
Q

the characteristic of “metal-rich stars (population I)” most appropriately belongs in which position of the galaxy

A

disk

87
Q

the characteristic of “clusters of hot young stars” most appropriately belongs in which position of the galaxy

A

disk

88
Q

the characteristic of “coplanar, circular stellar orbits” most appropriately belongs in which position of the galaxy

A

disk

89
Q

what can the radius of a stars orbit and its orbital velocity be used to estimate

A

the mass interior to the stars orbit

90
Q

what statement best describes the change in percentage of heavy elements of stars in the disk of the milky way galaxy over time

A

the percentage of heavy elements in disk stars increases over time

91
Q

what characteristic does the Hubble “tuning fork” diagram use to classify galaxies

A

a galaxies morphology

92
Q

what is a possible outcome of a merger between two small elliptical galaxies

A

a large elliptical galaxies

93
Q

why do stars in colliding galaxies not collide themselves

A

the distances between stars is very large compared to the sizes of the stars themselves

94
Q

what likely happened to an elliptical galaxy that appears to be populated by mostly cool, red main sequence stars

A

it has been around long enough such that the blue stars have evolved into the cool red main sequence stars we see

95
Q

in the early 20th century, astronomers deduced that the sun is not at the center of the milky way galaxy for what reason?

A

by observing the distribution of globular clusters in the halo of the galaxy

96
Q

what type of telescope would be best used to observe the distribution of cool, neutral hydrogen gas in a nearby galaxy

A

a radio telescope

97
Q

the ratio of the number of spiral galaxies to the number of elliptical galaxies is observed to have a specific value for nearby galaxies. how will this ratio change as the universe ages

A

it will decrease

98
Q

if the Schwarzschild radius for a 1 Msun black hole is 3 km, what is the Schwarzschild radius for a black hole having a mass of 100 Msun

A

300 km

99
Q

the characteristic of “composed of a spheroidal and disk component” most appropriately belongs in which type galaxy

A

spiral

100
Q

the characteristic of “very common in dense galaxy clusters” most appropriately belongs in which position of the galaxy

A

elliptical

101
Q

the characteristic of “no active star formation” most appropriately belongs in which position of the galaxy

A

elliptical

102
Q

the characteristic of “contains a large amount of hot young blue stars” most appropriately belongs in which position of the galaxy

A

spiral and irregular

103
Q

the characteristic of “the end result of a merger between two elliptical galaxies” most appropriately belongs in which position of the galaxy

A

spiral or elliptical

104
Q

what properties must a neutron star have it we are to observe it as a pulsar

A

must have a rapid motion, a strong magnetic field, a misaligned rotation and magnetic axis, a beam that sweeps periodically past earth

105
Q

study questions 35-40 on exam 3

A

ok

106
Q

imagine that you measure the distance to a galaxy to be 100 Mpc and its recessional velocity is only 7,000 km/s. what would the distance to a galaxy be if its recessional velocity is only 700 km/s?

A

10 Mpc

107
Q

how would an astronaut falling into a black hole be “spaghettified”

A

tidal forces - the pull of gravity at his/her feet would be much greater than at his/her head

108
Q

why do astronomers believe that nearly all galaxies are redshifted

A

spacetime between galaxies is stretching due to the big bang

109
Q

which two things are needed to determine a standard candle’s distance from earth

A

apparent brightness and luminosity

110
Q

true or false: disks contain lots of bright, hot blue stars but are completely devoid of cool faint red stars

A

false, the disks produces all types of stars, with faint low mass cool red stars being the most common

Astronomy (4 decks)

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