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Galaxy and Universe > Galaxy and Universe Final exam > Flashcards

Galaxy and Universe Final exam Flashcards

1
Q

What is the surface temperature of the sun

A

5800K

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2
Q

in the core of the sun where nuclear fusion takes place. which method is responsible for the transport of energy

A

Radiation

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3
Q

starting from the center of the sun moving outward, order the layers of the sun

A

radiative zone, convection zone, photosphere, chromosphere and corona

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4
Q

the temperature of the sun is approximately what temperature

A

15 x million kelvin

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5
Q

the majority of the suns energy come from what

A

hydrogen fusion

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6
Q

the energy that fuels the sun is generated from where

A

the core

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7
Q

what makes up 29% of the suns radius

A

the convective zone

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8
Q

plages that are around sun spots appear brighter because of what

A

higher temperature

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9
Q

what is associated with the solar magnetic field

A

sunspots, prominence, coronal mass ejections, solar flares

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10
Q

when will the sun likely stop being a main sequence star

A

around 5 billion year

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11
Q

what is the temperature of the corona

A

1,000,000 K

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12
Q

where does most of the light from the sun originate from

A

photosphere

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13
Q

what is the most important characteristic of a star

A

its mass

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14
Q

what is hotter a red star or a blue star

A

blue star

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15
Q

spectral class q

A

OBAFGKM

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16
Q

what spectral class is the sun

A

G2

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17
Q

After hydrogen what is the second highest element in a star

A

helium

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18
Q

what is the mass range for main sequence stars

A

0.08 to 100 M

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19
Q

stars located on the main sequence are called what

A

dwarf stars

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20
Q

on a typical H-R diagram where are the stars with the smallest radii located

A

lower left corner

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21
Q

the one property of a main-sequence star that determines all its other properties

A

its mass

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22
Q

In an H-R diagram stars with the coolest surface temperature and highest luminosity are found where in the diagram

A

upper right corner

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23
Q

stars that have the smallest radii are classified as what

A

white dwarfs

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24
Q

binary stars are the most important for the determination of stellar what

A

mass

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25
Q

a main-sequence star is unique because

A

nuclear fusion of hydrogen occurs in its core

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26
Q

at the end of the proton-proton chain of nuclear fusion in the sun, hydrogen nuclei have been converted into what?

A

helium nuclei

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27
Q

Radiative transfer

A

emission and absorption of gamma-ray photons repeatedly, slowly degrading to lower energy photons which work their way to the surface

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28
Q

convective transport

A

hot cells become buoyant and rise, cells cool and fall

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29
Q

Helioseismology

A

sun vibrates or rings in very complicated patterns

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30
Q

photosphere

A

origin of all the visible radiation, about 400Km in depth and with an average temperature of 5800K

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31
Q

Solar spectrum

A

photosphere is complicated with 100,000’s of absorption lines of more than 70 elements

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32
Q

chromosphere

A

average temperature of 10,000K

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33
Q

corona

A

outermost layer reaching temperature of 1 to 2 million K visible during solar eclipse or coronagraph

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34
Q

solar activity

A

effects of magnetic fields on charged particles which must move along lines of magnetic field

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35
Q

coronal mass ejections (CME’s)

A

occur in coronal holes mass loss gives rise to the solar wind

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36
Q

sunspots

A

rotate with periods of suns rotation faster at the equator and slower at higher latitudes. average of about 28 days

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37
Q

umbra

A

darker spot of sunspot about 2000K cooler than sun’s surface

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38
Q

sunspot cycle of solar activity

A

takes an average of 11 years

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39
Q

prominences

A

ejections of mass along magnetic lines

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40
Q

flares

A

violent eruptions with temperatures up to 20 million K source of intense Gamma and x-rays

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41
Q

measuring the color of stars gives us what

A

surface temperature

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42
Q

color indezx

A

B-V blue stars about -0.4 and cool red stars about +2.0

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43
Q

radial velocity

A

present only if star is moving towards or away from the observer

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44
Q

Tangential velocity or proper motion

A

only perpendicular to the line of sight

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45
Q

Radial velocity and Tangential velocity

A

add together to form space velocity

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46
Q

composition of the sun

A

74.5% H, 23.7% He, 1.8% metals

47
Q

stellar masses

A

most important property of stars

48
Q

binary stars

A

the means for finding masses. the more massive a star has a smaller more elliptical orbit and less massive star has a larger orbit

49
Q

visual binary

A

two stars seen slowly orbiting around their center of mass. can get the masses of both stars from this

50
Q

spectroscopic binary

A

seen as only a single point of light but on spectrum see two sets of absorption lines, cannot get masses directly

51
Q

Masses of stars on main sequence

A

vary from 0.07 to 100M

52
Q

Horizontal Axis of H-R diagram

A

represents temperature

53
Q

stars in upper right corner of H-R diagram

A

cool but very luminous supergiants

54
Q

stars in lower left corner of H-R diagram

A

very hot and very faint small white dwarfs

55
Q

stars in upper left corner of H-R diagram

A

very hot and luminous massive o stars

56
Q

stars in lower right corner of H-R diagram

A

cool and small. Red dwarfs

57
Q

what classifies stars to be on the main sequence of H-R diagram

A

hydrogen being fused into helium in their core

58
Q

class Ia and Ib stars

A

supergiants

59
Q

class II stars

A

bright giants

60
Q

Class III stars

A

giants

61
Q

class IV stars

A

sub giants

62
Q

Cepheid and RR lyrae stars

A

pulsating variable stars

63
Q

cepheids

A

light curve gives the period of the star. have periods of 3 to 50 days and can be seen for 60 million light years

64
Q

period luminosity relation

A

transforms period into luminosity which is compared to a stars apparent brightness

65
Q

Trigonometric parallex

A

using baseline of diameter of earths orbit to measure the distance of a star. parallex is the angle star appears to be moving using radius of earths orbit as the baseline

66
Q

1 parsec

A

3.26 light years

67
Q

Absolute magnitude

A

is the apparent magnitude it would appear to be at a hypothetical distance of 10 parsecs

68
Q

a type II supernova

A

is the result of iron core collapse of a massive star

69
Q

what ionizes the gas in a planetary nebula and makes it visible

A

ultraviolet photons emitted by a hot central star

70
Q

a nova is the result of which explosive situation

A

mass transfer onto a white dwarf

71
Q

astronomers use the term interstellar reddening to refer to

A

the scattering of starlight by dust grains in space

72
Q

a type of star that has turned out to be extremely useful for measuring distances

A

cepheid variables

73
Q

an iron core cannot support a massive main-sequence star because of what

A

iron cannot fuse to make heavier nuclei and produce energy

74
Q

a white dwarf star has a diameter of approximately what

A

the earth

75
Q

a type I supernova occurs when a white dwarf exceeds the mass of what

A

1.4 solar masses

76
Q

a light curve for a star measures how its brightness changes with

A

time

77
Q

what type of main sequence star is most likely to become a black hole

A

G star

78
Q

what characteristic of a star cluster is used to determine its age

A

by comparing the main sequence turnoff in the clusters HR diagram to theoretical models

79
Q

as a high-mass-main sequence star evolves off the main sequence it follow a

A

roughly horizontal path on the H-R diagram

80
Q

an HII region

A

a zone around a hot star where hydrogen atoms are ionized

81
Q

helium burns in the core of a horizontal branch star via __ and produces __

A

the triple-alpha reaction and carbon

82
Q

what critical events have signaled that a star has reached the main-sequence

A

the fusion of Hydrogen in Helium begins in the core

83
Q

the region around a black hole where everything is trapped and nothing can get out to interact with the rest of the universe

A

the even horizon

84
Q

in a white dwarf, what is the source of pressure that halts its contraction as it cools

A

electrons packed so closely that they become degenerate

85
Q

massive stars synthesize chemical elements going from helium up to what in the core

A

iron

86
Q

which of the properties of a star typically requires a knowledge of distance before it can be determined

A

luminosity

87
Q

essentially all the elements heavier than iron in our milky way were formed by what

A

supernovae or merging neutron stars

88
Q

a young protostar with a mass of 1 solar masses as it evolves will move

A

vertically downward in the H-R diagram

89
Q

when a star equal to the mass of the sun dies, it will become what?

A

a white dwarf

90
Q

a type of cluster that contains really old stars

A

globular cluster

91
Q

which stage of nuclear fusion is the last to occur in the core of a massive star

A

silicon fusion to iron

92
Q

the path that a forming star follows as its position in the H-R diagram changes with time is called what

A

its evolutionary track

93
Q

interstellar dust

A

seen as dark clouds silhouetted against a dark background

94
Q

interstellar extinction

A

stars appear fainter

95
Q

interstellar reddening

A

stars appear redder

96
Q

molecular clouds

A

densest interstellar clouds whose temperature reach as low as 10K

97
Q

star formation

A

results in UV radiation from O and B stars that ionize their immediate surroundings

98
Q

surface temperature of protostar

A

remains constant while collapse is slowly taking place and core is heating up. star is shrinking and surface area is less and its luminosity is decreasing

99
Q

main sequence turnoff

A

point on the main sequence where stars are just leaving the main sequence gives the age of the cluster

100
Q

Low-mass stellar evolution

A

H fuel core of sun will be exhausted. He core collapses to a small radius. Dense and finds support from electron degeneracy (electrons cannot be pushed any closer)

101
Q

Hydrogen shell burning

A

luminosity of star increases and outer region of star expands. becomes a subgiant and then a red giant

102
Q

Helium core burning

A

Triple-alpha process. core temperature increases rapidly. star moves down onto He burning main sequence. now burning He in the core and H in the shell

103
Q

Hydrogen and Helium shell burning

A

He is exhausted in the core it collapses again. Goes to second red giant branch lose large amounts of mass total of 30-50% of total mass

104
Q

white dwarf

A

limit of 1.4M moves down to the left of the H-R diagram becomes the size of the earth after many years will become a black dwarf

105
Q

Type Ia supernova

A

when a white dwarf exceeds 1.4M leftover iron and nickel shot out into space

106
Q

Neutron star

A

core of supernova left behind maximum of 3M supported by electron degeneracy

107
Q

pulsar

A

Electrons and Protons are caught in the magnetic field and beamed out in 2 narrow beams

108
Q

black hole

A

mass of a core of a supernova exceeds 3M it collapses into a black hole

109
Q

elliptical galaxies

A

E0 to E7 circular to elliptical shaped with their appearance depending upon their orientation. no star formation and no gas and dust

110
Q

spiral galaxies

A

flattened rotating disks and spiral arms stars are forming

111
Q

spiral arms

A

ongoing star formation locations of where clouds of interstellar gas is compressed

112
Q

spiral density waves

A

spiral pattern associated with the disks rotation

113
Q

Dark matter

A

90% of mass in a galaxy is dark matter

Galaxy and Universe (8 decks)

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