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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
Q

Radial Velocity

A

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

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26
Q

Tangential Velocity (Proper Motion)

A

only perpendicular to the line of sight

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27
Q

space velocity

A

Radial Velocity and tangential velocity work together to make this

28
Q

Composition of the sun

A

74.5% Hydrogen, 23.7% Helium 1.8% metals

29
Q

Luminosity

A

depends on R2 and T4

30
Q

Stellar masses

A

most important property of stars

31
Q

Binary Stars

A

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

32
Q

visual binary

A

two stars slowly orbiting about their centre of mass. can get masses of the two stars

33
Q

Spectroscopic binary

A

seen as only a single point of light. but in spectrum 2 sets of absorption lines. Can’t get mass directly

34
Q

Eclipsing binary

A

orbit is almost edge-on. see one star eclipse the other. give radius and temperature of each star

35
Q

Masses

A

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
Q

Vertical axis of H-R Diagram

A

luminosity

37
Q

Horizontal axis of H-R Diagram

A

Temperature, spectral type or color index B-V

38
Q

Stars in upper right corner of H-R diagram

A

cool, very luminous large (super giants)

39
Q

stars in lower left corner of H-R diagram

A

very hot, but faint very small (white dwarfs)

40
Q

stars in the upper left corner of H-R diagram

A

very hot and luminous massive O stars

41
Q

Stars in the lower right corner of H-R diagram

A

cool and small, low mass red dwarfs

42
Q

The main sequence H-R diagram

A

all stars which hydrogen is being fused into helium

43
Q

classes Ia and Ib

A

supergiants

44
Q

classes II stars

A

bright giants

45
Q

Classes III stars

A

giants

46
Q

class IV stars

A

sub giants

47
Q

class V stars

A

dwarfs (main sequence)

48
Q

What is the average sun spot cycle

A

11 years

49
Q

What is the temperature of the core of the sun around?

A

15 million kelvin

50
Q

Detection of Neutrinos

A

predicted rate by standard model of the sun. Neutrinos have very little mass and travel at almost the speed of light

51
Q

Neutrinos

A

are very un-reactive and leave the sun in 2 seconds and takes about 8 minutes to reach the earth

52
Q

What is the depth of the photo sphere

A

around 400 km

53
Q

Magnitude system

A

smaller magnitudes represent brighter stars and larger magnitudes represent dimmer stars

54
Q

Apparent magnitude

A

brightness as a star as it appears in the sky

55
Q

Absolute magnitude

A

Can be measured by apparent magnitude with distance. also referred to as luminosity

56
Q

colour index

A

B-V. Blue stars are negative at about -0.4 and red stars are positive at about +2.0

57
Q

Surface temperature

A

The hotter the surface of a star the more blue it is the cooler the more red colour

58
Q

pulsating variable stars

A

RR lyrae and cepheids

59
Q

Cepheids

A

light curve gives the period of the star.

60
Q

period luminosity relation

A

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
Q

cepheid periods

A

about 3 to 50 days and luminosity from 1000 to 10 000L they can be seen as far as 60 million light years

62
Q

RR Lyrae

A

Have shorter periods and lower luminosities than cepheid

63
Q

Trigonometric Parallax

A

fundamental basis of distance measurement. using baseline of diamater of Earth orbit to measure distance of a star

64
Q

Parallax

A

angle stars appear to move using Radius of earth orbit as the baseline

65
Q

Parsec

A

1 parsec is 3.26 light years

66
Q

Gaia

A

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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