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Astronomy > Test 3 > Flashcards

Test 3 Flashcards

0
Q

RR Lyraes stars

A 
Round a 1/2 day period. 
Old stars
Low mass
Low metallicity
Usually found in globular clusters
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1
Q

Instability strips

A

Region on the HR diagram where variable stars are found.

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2
Q

Cepheid variable stars

A 
1-100 day period 
Young stars
High metallicity 
High mass
Found in open clusters or disk
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3
Q

Constellation at middle of Milky Way galaxy

A

Sagittarius

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4
Q

Shapely

A

He found RR Lyrae stars in globular clusters and determined we are not at the center of the galaxy

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5
Q

Edwin Hubble

A

Used the hooker telescope and found cepheid variable stars in andromeda galaxy proving it was a whole nother galaxy not just a star forming region within our galaxy

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6
Q

Used to map the spiral arms of the Milky Way galaxy

A

Hydrogen spin-flip transition

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7
Q

Halo

A 
No gas and dust
Old stars
Metal poor
Population II stars
Globular clusters
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8
Q

Disk

A 
Gas and dust
Young stars
Emission nebulas 
Star formation, GMCs
Open clusters
Population I stars
Metal rich
Sun
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9
Q

Bulge

A

Contains population I and II stars

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10
Q

Forming spiral arms

A

1) star formation propagation

2) density wave theory

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11
Q

Milky Way rotation

A

Use Doppler effect

V = 230 km/sec

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12
Q

Galactic year

A

The time it takes to go around the center of the galaxy.

One galactic year for the sun: t= 200,000,000 - 250,000,000 years
So sun is about 22 galactic years old

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13
Q

Mass of Milky Way

A

m = 9.4 * 10^10 solar masses

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14
Q

Number of stars in the Milky Way.

A

200,000,000,000 stars

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15
Q

Dark matter

A

For the outside of the galaxy to be goin as fast as the center of the galaxy there must be more mass that can’t be seen.
Missing mass.
The effects of it’s gravity can be seen but not what’s causing it.
WIMP: Google

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16
Q

Center of Milky Way

A

Super massive black hole.
Sgr A: 3,000,000 solar masses
There’s that much mass in a spot smaller than the solar system

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17
Q

Spiral galaxies

A 
Gas and dust
Orbits with a plane
Young O&B stars
Open and globular clusters
Blue
Metal-rich
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18
Q

Elliptical galaxies

A 
Very little gas and dust
Random orbits
Old stars
Globular clusters
Red
Metal poor
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19
Q

Poor clusters

A

About 30 galaxies in a group

Local group: MW, andromeda, etc (about 25)

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20
Q

Rich clusters

A

1000s of galaxies

Giant ellipticals usual found at center

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21
Q

Super clusters

A

Clusters of galaxy clusters

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22
Q

Large scale structure of the universe

A

Voids: regions without galaxies

Galaxies cluster together in long filaments

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23
Q

What type of galaxy cluster is the Milky Way apart of?

A

Poor

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24
Q

What are the 2 closest galaxies to the Milky Way?

A

Large and small Magellanic Clouds.

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25
Q

What is a quasar seen from the side called?

A

Radio galaxy

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26
Q

What type of star cluster contains population type II objects?

A

Globular cluster

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27
Q

What type of galaxy contain the least gas and dust?

A

Ellipticals

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28
Q

Who was the first to determine the distance to the Andromeda galaxy by using Chepheid variable stars?

A

Edwin Hubble

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29
Q

Which galaxy type is the oldest?

A

All are the same age

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30
Q

Can two colliding elliptical galaxies make a spiral?

A

No

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31
Q

What type of variable stars are found in globular clusters and were used by Harlow Shapely in determining distances to globular clusters?

A

RR Lyraes

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32
Q

What is the size of a black hole with 10 solar masses of material?

A

R= 3(10) = 30 km

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33
Q

What type of galaxy is the Milky Way?

A

Spiral

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34
Q

Which type of galaxy is the reddest?

A

Ellipticals

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35
Q

Which is true for a semi-detached binary system?
A) both stars fill their Roche lobes
B) matter is being transferred from one star to the other through the L1 point.
C) both stars share a common envelope.
D) the stars can be used to determine distances to other galaxies
E) none of the above

A

B

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36
Q

Which of the following characteristics do all cluster stars not have in common?
A) mass
B) age
C) composition
D) distance
E) all of the above are common to cluster stars

A

A

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37
Q

Which galaxy type used up most of its gas and dust early in it’s history?

A

Ellipticals

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38
Q

Which of the following is true about the large scale structure of the universe?
A) galaxies are uniformly distributed in the universe
B) all galaxies are at the center of the universe with only a few at the edges
C) the galaxies are distributed on the edge of bubbles with nothing in some regions
D) the nearby quasars are much more numerous than the distant quasars
E) none of the above

A

C

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39
Q

Which of the following is not true about quasars?
A. they have high redshifts
B. They emit a lot of energy
C. They are equivalent to radio galaxies just seen from a different angle.
D. They are much more numerous when the universe was much younger.
E. All the the above are true about quasars.

A

E.

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40
Q

What is it called when distant light is bent by closer objects?

A

Gravitational lensing

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41
Q

Which of the following is not true of spiral galaxies?
A. The disk of the galaxy has circular orbits all in the same direction.
B. gas and dust are only found in the halo of the galaxies.
C. They have a bluer colour.
D. They contain population I and II stars.
E. All of the above are true for spiral galaxies.

A

B.

42
Q

Hubble law

A

The further a galaxy is away from us, the faster it is moving away.

43
Q

LaGrangian points

A

Points of gravitational equilibrium in a 3 body system

44
Q

Large and small Magellanic Clouds

A

Companion galaxies of the Milky Way.

45
Q

Z value

A

Change in wavelength over rest wavelength.

46
Q

Light element abundances

A

The amount of H, He, Li, Be in the universe matches the prediction of the Big Bang theory.

47
Q

Harlow shapely

A

First one to determine the center of the Milky Way using globular clusters

48
Q

Center of Milky Way

A

In Sagittarius where a super massive black hole resides

49
Q

Forming spiral arms

A

Two methods:
Star formation
Density wave

50
Q

Which are the largest galaxies in the universe?

A

Giant ellipticals

51
Q

What is the group of galaxies containing over a thousand galaxies called?

A

Rich cluster

52
Q

What does quasar stand for?

A

Quasi stellar radio source

53
Q

Which region of the galaxy contains globular clusters?

A

Halo

54
Q

What’s the current temperature of the background radiation?

A

3 K or 2.72 K

55
Q

What type of stars did Shapely use to determine the distance to globular clusters?

A

RR Lyraes

56
Q

What is the suspected classification of the Milky Way galaxy?

A

SBb

57
Q

What is it called when a small galaxy collides with a large galaxy?

A

Galactic cannibalism

58
Q

What is the name for a binary star system in which both stars fill their Roche lobes?

A

Contact binary

59
Q

What is the name for a galaxy which is currently showing a large amount of star formation?

A

Starburst

60
Q

Who was the first to determine the shape of the Milky Way galaxy and that we weren’t at the center?

A

Harlow shapely

61
Q

Who first determined the distance to the Andromeda galaxy?

A

Hubble

62
Q

Which galaxy type has the most gas and dust?

A

Irregulars

63
Q

Which galaxies formed first?

A

All formed at the same time

64
Q

How many years does it take the sun to orbit the Milky Way?

A

250,000,000

65
Q

Which type of galaxy has almost all population II stars?

A

Ellipticals

66
Q

Which of the following is not a method for determining distances?
A. Cepheid variable stars
B. galactic parallax
C. Brightest stars in a galaxy
D. Supernova type I
E. All are methods for determining distances

A

B.

67
Q

Collision between galaxies can:
A. Turn ellipticals into spirals
B. cause all the stars in both galaxies to collapse into super massive black holes
C. Cause bursts of star formation
D. Cause large numbers of stars to collide and explode.
E. All of the above
F. None of the above

A

C.

68
Q 
What is it called when distant light is bent by nearer objects?
A. Space-time distortions
B. large-scale warping
C. Einstein field equations
D. Relativistic bending
E. None of the above
A

E.

69
Q

What allows astronomers to map the positions of the Milky Way’s spiral arms?

A

The spin-flip transmission of a hydrogen atom

70
Q

Quasar

A

Quasi stellar radio source. Objects which look like stars but are actually extremely distant galaxies

71
Q

Dark matter

A

Matter who’s gravitational influence can be detected but it can’t be seen

72
Q

Algol paradox

A

The more massive star in the binary star system is the least evolved

73
Q

Population II objects

A

Old objects
Metal poor
Found in halo and globular clusters

74
Q

Open cluster

A

Cluster of young stars with about 100 stars lying in the disk of the galaxy

75
Q

Event horizon

A

Point around a black hole where escape velocity equals the speed of light

76
Q

Galactic cannibalism

A

When a larger galaxy swallows a smaller one

77
Q

Write Hubble’s law and explain what it implies

A

Further a galaxy is, the faster it’s moving.

Implies the universe is expanding

78
Q

What is usually found in the center of rich clusters of galaxies?

A

Giant ellipticals

79
Q

Which region of the galaxy contains open clusters?

A

Disk

80
Q

What did Penzias and Wilson discover with their microwave antenna?

A

Background radiation

81
Q

Who invented the tuning fork diagram to classify galaxies?

A

Hubble

82
Q

Which is not true of giant elliptical galaxies?
A. They have many globular clusters
B. they are found at the centers of rich clusters of galaxies
C. They are most likely formed by the collision of other galaxies
D. They are redder in colour than spiral galaxies
E. All of the above are true

A

E.

83
Q

Which is the most likely theory for the formation of galaxies?
A. Many smaller clumps merged into galaxies
B. one large clump collapsed into a galaxy

A

A.

84
Q

In the GUTs (grand unified theory) which of the four forces was the first to seperate?

A

Gravity

85
Q

Colliding galaxies

A

Gas and dust hits each other

Stars rarely collide

86
Q

starburst galaxies

A

High amount of star formation.

Occurs after galactic cannibalism

87
Q

Galaxy formation theories

A
  1. Start with a large cloud of gas and dust that collapses

2. Many small clouds come together. Most likely theory!!!

88
Q

Hubble’s constant

A 
H = V/D
H = 67.80 + or - .77 km/sec/mpc
89
Q

Age of universe

A 
t = 1000/H
t = about 13 billion years
90
Q

Distance to galaxies

A
  1. Variable stars
  2. Brightest stars
  3. Brightest globular cluster
  4. Supernova explosions
  5. Brightest galaxy in clusters
  6. Hubble’s law
91
Q

Sky at many wavelengths

A

Radiowaves: detects gas

Microwaves: everywhere

Infrared: dust

Optical (visible)

Ultraviolet: everywhere. Hot gas.

X-rays: gas at millions of degrees

Gamma rays: supernova explosions. Collision of black holes

92
Q

Quasars are:

A

Really small
Very far
Very powerful

93
Q

Radio galaxies

A

Giant streams of stuff shooting out of galaxies perpendicular to the disk.

94
Q

Gravitational lensing

A

When mass bends light.

Proves dark matter because there isn’t enough mass to bend the light

95
Q

Cosmology

A

Study of the universe as a whole

96
Q

Who discovered background radiation?

A

Penzias and Wilson

97
Q

Temperature of background radiation?

A

3 degrees Kelvin

98
Q

3 pieces of evidence for the Big Bang theory

A
  1. Universe is expanding so it had to start from a single point
  2. Background radiation
  3. Light element abundances
99
Q

GUTs

A

Grand unified theory

the 4 natural forces were at one time unified as one force.

100
Q

4 natural forces

A
  1. Strong nuclear force
  2. Weak nuclear force
  3. Electromagnetic force
  4. Gravity
101
Q

Big Bang theory

A

10^-43 : gravity seperates from the one force.

10^-36 : inflationary epoch. Strong force separates.

10^-34 : leptons, quarks, etc.

10^-10 : weak and electromagnetic forces separate

3 min ABB : H –> He

500,000 ABB : background radiation is created

100,000,000 ABB : first stars

1,000,000,000 ABB : galaxies

102
Q

Equation to get distance

A

H (Hubble’s constant) = V/D

Astronomy (2 decks)

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