Galaxy and Universe Final exam Flashcards
(113 cards)
1
Q
What is the surface temperature of the sun
A
5800K
2
Q
in the core of the sun where nuclear fusion takes place. which method is responsible for the transport of energy
A
Radiation
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
4
Q
the temperature of the sun is approximately what temperature
A
15 x million kelvin
5
Q
the majority of the suns energy come from what
A
hydrogen fusion
6
Q
the energy that fuels the sun is generated from where
A
the core
7
Q
what makes up 29% of the suns radius
A
the convective zone
8
Q
plages that are around sun spots appear brighter because of what
A
higher temperature
9
Q
what is associated with the solar magnetic field
A
sunspots, prominence, coronal mass ejections, solar flares
10
Q
when will the sun likely stop being a main sequence star
A
around 5 billion year
11
Q
what is the temperature of the corona
A
1,000,000 K
12
Q
where does most of the light from the sun originate from
A
photosphere
13
Q
what is the most important characteristic of a star
A
its mass
14
Q
what is hotter a red star or a blue star
A
blue star
15
Q
spectral class q
A
OBAFGKM
16
Q
what spectral class is the sun
A
G2
17
Q
After hydrogen what is the second highest element in a star
A
helium
18
Q
what is the mass range for main sequence stars
A
0.08 to 100 M
19
Q
stars located on the main sequence are called what
A
dwarf stars
20
Q
on a typical H-R diagram where are the stars with the smallest radii located
A
lower left corner
21
Q
the one property of a main-sequence star that determines all its other properties
A
its mass
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
23
Q
stars that have the smallest radii are classified as what
A
white dwarfs
24
Q
binary stars are the most important for the determination of stellar what
A
mass
25
a main-sequence star is unique because
nuclear fusion of hydrogen occurs in its core
26
at the end of the proton-proton chain of nuclear fusion in the sun, hydrogen nuclei have been converted into what?
helium nuclei
27
Radiative transfer
emission and absorption of gamma-ray photons repeatedly, slowly degrading to lower energy photons which work their way to the surface
28
convective transport
hot cells become buoyant and rise, cells cool and fall
29
Helioseismology
sun vibrates or rings in very complicated patterns
30
photosphere
origin of all the visible radiation, about 400Km in depth and with an average temperature of 5800K
31
Solar spectrum
photosphere is complicated with 100,000's of absorption lines of more than 70 elements
32
chromosphere
average temperature of 10,000K
33
corona
outermost layer reaching temperature of 1 to 2 million K visible during solar eclipse or coronagraph
34
solar activity
effects of magnetic fields on charged particles which must move along lines of magnetic field
35
coronal mass ejections (CME's)
occur in coronal holes mass loss gives rise to the solar wind
36
sunspots
rotate with periods of suns rotation faster at the equator and slower at higher latitudes. average of about 28 days
37
umbra
darker spot of sunspot about 2000K cooler than sun's surface
38
sunspot cycle of solar activity
takes an average of 11 years
39
prominences
ejections of mass along magnetic lines
40
flares
violent eruptions with temperatures up to 20 million K source of intense Gamma and x-rays
41
measuring the color of stars gives us what
surface temperature
42
color indezx
B-V blue stars about -0.4 and cool red stars about +2.0
43
radial velocity
present only if star is moving towards or away from the observer
44
Tangential velocity or proper motion
only perpendicular to the line of sight
45
Radial velocity and Tangential velocity
add together to form space velocity
46
composition of the sun
74.5% H, 23.7% He, 1.8% metals
47
stellar masses
most important property of stars
48
binary stars
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
visual binary
two stars seen slowly orbiting around their center of mass. can get the masses of both stars from this
50
spectroscopic binary
seen as only a single point of light but on spectrum see two sets of absorption lines, cannot get masses directly
51
Masses of stars on main sequence
vary from 0.07 to 100M
52
Horizontal Axis of H-R diagram
represents temperature
53
stars in upper right corner of H-R diagram
cool but very luminous supergiants
54
stars in lower left corner of H-R diagram
very hot and very faint small white dwarfs
55
stars in upper left corner of H-R diagram
very hot and luminous massive o stars
56
stars in lower right corner of H-R diagram
cool and small. Red dwarfs
57
what classifies stars to be on the main sequence of H-R diagram
hydrogen being fused into helium in their core
58
class Ia and Ib stars
supergiants
59
class II stars
bright giants
60
Class III stars
giants
61
class IV stars
sub giants
62
Cepheid and RR lyrae stars
pulsating variable stars
63
cepheids
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
period luminosity relation
transforms period into luminosity which is compared to a stars apparent brightness
65
Trigonometric parallex
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
1 parsec
3.26 light years
67
Absolute magnitude
is the apparent magnitude it would appear to be at a hypothetical distance of 10 parsecs
68
a type II supernova
is the result of iron core collapse of a massive star
69
what ionizes the gas in a planetary nebula and makes it visible
ultraviolet photons emitted by a hot central star
70
a nova is the result of which explosive situation
mass transfer onto a white dwarf
71
astronomers use the term interstellar reddening to refer to
the scattering of starlight by dust grains in space
72
a type of star that has turned out to be extremely useful for measuring distances
cepheid variables
73
an iron core cannot support a massive main-sequence star because of what
iron cannot fuse to make heavier nuclei and produce energy
74
a white dwarf star has a diameter of approximately what
the earth
75
a type I supernova occurs when a white dwarf exceeds the mass of what
1.4 solar masses
76
a light curve for a star measures how its brightness changes with
time
77
what type of main sequence star is most likely to become a black hole
G star
78
what characteristic of a star cluster is used to determine its age
by comparing the main sequence turnoff in the clusters HR diagram to theoretical models
79
as a high-mass-main sequence star evolves off the main sequence it follow a
roughly horizontal path on the H-R diagram
80
an HII region
a zone around a hot star where hydrogen atoms are ionized
81
helium burns in the core of a horizontal branch star via __ and produces __
the triple-alpha reaction and carbon
82
what critical events have signaled that a star has reached the main-sequence
the fusion of Hydrogen in Helium begins in the core
83
the region around a black hole where everything is trapped and nothing can get out to interact with the rest of the universe
the even horizon
84
in a white dwarf, what is the source of pressure that halts its contraction as it cools
electrons packed so closely that they become degenerate
85
massive stars synthesize chemical elements going from helium up to what in the core
iron
86
which of the properties of a star typically requires a knowledge of distance before it can be determined
luminosity
87
essentially all the elements heavier than iron in our milky way were formed by what
supernovae or merging neutron stars
88
a young protostar with a mass of 1 solar masses as it evolves will move
vertically downward in the H-R diagram
89
when a star equal to the mass of the sun dies, it will become what?
a white dwarf
90
a type of cluster that contains really old stars
globular cluster
91
which stage of nuclear fusion is the last to occur in the core of a massive star
silicon fusion to iron
92
the path that a forming star follows as its position in the H-R diagram changes with time is called what
its evolutionary track
93
interstellar dust
seen as dark clouds silhouetted against a dark background
94
interstellar extinction
stars appear fainter
95
interstellar reddening
stars appear redder
96
molecular clouds
densest interstellar clouds whose temperature reach as low as 10K
97
star formation
results in UV radiation from O and B stars that ionize their immediate surroundings
98
surface temperature of protostar
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
main sequence turnoff
point on the main sequence where stars are just leaving the main sequence gives the age of the cluster
100
Low-mass stellar evolution
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
Hydrogen shell burning
luminosity of star increases and outer region of star expands. becomes a subgiant and then a red giant
102
Helium core burning
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
Hydrogen and Helium shell burning
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
white dwarf
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
Type Ia supernova
when a white dwarf exceeds 1.4M leftover iron and nickel shot out into space
106
Neutron star
core of supernova left behind maximum of 3M supported by electron degeneracy
107
pulsar
Electrons and Protons are caught in the magnetic field and beamed out in 2 narrow beams
108
black hole
mass of a core of a supernova exceeds 3M it collapses into a black hole
109
elliptical galaxies
E0 to E7 circular to elliptical shaped with their appearance depending upon their orientation. no star formation and no gas and dust
110
spiral galaxies
flattened rotating disks and spiral arms stars are forming
111
spiral arms
ongoing star formation locations of where clouds of interstellar gas is compressed
112
spiral density waves
spiral pattern associated with the disks rotation
113
Dark matter
90% of mass in a galaxy is dark matter
