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Galaxy and Universe > Galaxy and Universe midterm #1 > Flashcards

Galaxy and Universe midterm #1 Flashcards

1
Q

What percentage is the radiative zone

A

71%

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2
Q

What percentage is the convection zone

A

29%

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3
Q

What kind of star is the sun

A

G2

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4
Q

What is radiative transfer

A

emission and absorption of Gamma-ray photons, repeatedly. slowly degrading to lower energy photons which works their way up to the surface

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5
Q

What is convection transport

A

hot cells become buoyant and rise, cells cool and fall

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6
Q

how many types of Neutrinos are there

A

3

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7
Q

Helioseismology

A

sun vibrates or rings in very complicated patterns

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8
Q

What part of the sun do we see

A

The photosphere

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9
Q

What temperature is the photosphere

A

5800K

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10
Q

What is the average temperature of the chromosphere

A

10,000K

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11
Q

When is the Corona visible

A

During a solar eclipse or using a coronagraph

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12
Q

What is the average temperature of the Corona

A

1 to 2 million K

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13
Q

What is Solar activity

A

Effects on Magnetic Fields of charged particles which must move along lines of magnetic field

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14
Q

Coronal Mass Ejection (CME’s)

A

occurs in coronal holes and is mass loss gives rise to solar wind

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15
Q

Umbra

A

Dark part of sunspot about 2000K cooler than suns surface

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16
Q

penumbra

A

outer of sunspot can be 1000k cooler than suns surface

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17
Q

What produces sun spots

A

Magnetic field

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18
Q

Maunder Minimum

A

1645-1715 no sunspots and extremely cold winters on earth

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19
Q

Prominences

A

ejections of mass along magnetic lines

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20
Q

Flares

A

violent eruptions temperature up to 20 million K intense X-Rays and Gamma-Rays

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21
Q

Spectral Sequence

A

OBAFGKM

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22
Q

1st Step of proton-proton chain

A

2 Hydrogen fuse makes a neutrino, positron and 2H (Deuterium) repeats twice

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23
Q

2nd step of proton-proton chain

A

Deuterium (2H) and 1H fuse and make 3He and gives off a gamma-ray repeats twice

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24
Q

3rd step of Proton-proton chain

A

2 3He fuse and throws out 4He but also gives 2 Hydrogens overall loss of 0.7 of original mass

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25
Radial Velocity
present only if the star is moving toward or away from observer
26
Tangential Velocity (Proper Motion)
only perpendicular to the line of sight
27
space velocity
Radial Velocity and tangential velocity work together to make this
28
Composition of the sun
74.5% Hydrogen, 23.7% Helium 1.8% metals
29
Luminosity
depends on R2 and T4
30
Stellar masses
most important property of stars
31
Binary Stars
means for finding masses. more massive star has smaller orbit less massive has a larger orbit
32
visual binary
two stars slowly orbiting about their centre of mass. can get masses of the two stars
33
Spectroscopic binary
seen as only a single point of light. but in spectrum 2 sets of absorption lines. Can't get mass directly
34
Eclipsing binary
orbit is almost edge-on. see one star eclipse the other. give radius and temperature of each star
35
Masses
vary from 0.075M (M stars) to 100 (rare O stars) even 250M (very rare) 0.08M minimum mass able to ignite nuclear fusion of hydrogen to helium
36
Vertical axis of H-R Diagram
luminosity
37
Horizontal axis of H-R Diagram
Temperature, spectral type or color index B-V
38
Stars in upper right corner of H-R diagram
cool, very luminous large (super giants)
39
stars in lower left corner of H-R diagram
very hot, but faint very small (white dwarfs)
40
stars in the upper left corner of H-R diagram
very hot and luminous massive O stars
41
Stars in the lower right corner of H-R diagram
cool and small, low mass red dwarfs
42
The main sequence H-R diagram
all stars which hydrogen is being fused into helium
43
classes Ia and Ib
supergiants
44
classes II stars
bright giants
45
Classes III stars
giants
46
class IV stars
sub giants
47
class V stars
dwarfs (main sequence)
48
What is the average sun spot cycle
11 years
49
What is the temperature of the core of the sun around?
15 million kelvin
50
Detection of Neutrinos
predicted rate by standard model of the sun. Neutrinos have very little mass and travel at almost the speed of light
51
Neutrinos
are very un-reactive and leave the sun in 2 seconds and takes about 8 minutes to reach the earth
52
What is the depth of the photo sphere
around 400 km
53
Magnitude system
smaller magnitudes represent brighter stars and larger magnitudes represent dimmer stars
54
Apparent magnitude
brightness as a star as it appears in the sky
55
Absolute magnitude
Can be measured by apparent magnitude with distance. also referred to as luminosity
56
colour index
B-V. Blue stars are negative at about -0.4 and red stars are positive at about +2.0
57
Surface temperature
The hotter the surface of a star the more blue it is the cooler the more red colour
58
pulsating variable stars
RR lyrae and cepheids
59
Cepheids
light curve gives the period of the star.
60
period luminosity relation
transforms period into luminosity which is compared to the stars apparent brightness giving the distance to the cepheid and the cluster in which the cepheid is located
61
cepheid periods
about 3 to 50 days and luminosity from 1000 to 10 000L they can be seen as far as 60 million light years
62
RR Lyrae
Have shorter periods and lower luminosities than cepheid
63
Trigonometric Parallax
fundamental basis of distance measurement. using baseline of diamater of Earth orbit to measure distance of a star
64
Parallax
angle stars appear to move using Radius of earth orbit as the baseline
65
Parsec
1 parsec is 3.26 light years
66
Gaia
satellite that will get distances to 30 000 light years for 1.7 billion stars. will reach the center of galaxy

Galaxy and Universe (8 decks)

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