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ASTR 1102 > Exam #3 > Flashcards

Exam #3 Flashcards

1
Q

Chemical composition of the sun.

A
  • 72% hydrogen
  • 27% helium
  • 1% metals
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2
Q

density

A

number of particles (mass) per unit volume.

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3
Q

Two gas clouds floating in space have the same temperature (so the atoms/molecules have the same speed). Both have the same volume, but one cloud is low mass (low density) while the other is very massive (high density). Which one will have more self-gravity? That is, in which cloud will the force of gravity be able to hold it together in spite of the motion of the atoms/molecules?

A

the high density cloud.

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4
Q

You create two clouds of gas floating in space. Both have the same mass and start out with the same volume. However, one is very hot while the other is very cold. In which cloud of gas is it more likely that the force of gravity will be able to win out over the motion of the atoms/molecules?

A

the cold cloud.

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5
Q

You create two clouds of gas floating in space. Both have the same mass and start out with the same volume. However, one is very hot while the other is very cold. In which cloud of gas is it more likely that the force of gravity will be able to win out over the motion of the atoms/molecules?

A

the cold cloud.

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6
Q

Stars spend ___% of their lifetimes on the main sequence.

A

90

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7
Q

What controls how long stars live?

A

Mass

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8
Q

Consider the information given below about three main sequence stars:
A will be on the main sequence for 45 billion years. B will be on the main sequence for 100 million years. C will be on the main sequence for 2 million years.
Which of the following statements is true?

A. Star A has the greatest mass
B. Star B has the greatest mass
C. Star C has the greatest mass
D. all main sequence stars have about the same mass

A

Star C has the greatest mass.

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9
Q

Consider the information given below about three main sequence stars:
A will be on the main sequence for 45 billion years. B will be on the main sequence for 100 million years. C will be on the main sequence for 2 million years.
Which of the following statements is true?

A. Star A the coolest
B. Star B is the coolest
C. Star C is the coolest
D. all main sequence stars the same temperature

A

Star A is the coolest.

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10
Q

Consider the information given below about three main sequence stars:
A will be on the main sequence for 45 billion years. B will be on the main sequence for 100 million years. C will be on the main sequence for 2 million years.
Which of the following statements is true?

A. Star A the coolest
B. Star B is the coolest
C. Star C is the coolest
D. all main sequence stars the same temperature

A

Star A is the coolest.

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11
Q

Which of the following statements is correct?
A. a star with 10 times the mass of the sun will live 10 times longer than the sun
B. a star with 10 times the mass of the sun will live more than 10 times longer than the sun
C. a star with 10 times the mass of the sun will live 1/10 as long as the sun
D. a star with 10 times the mass of the sun will live less than 1/10 as long as the sun

A

A star with 10 times the mass of the sun will live less than 1/10 as long as the sun.

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12
Q

Blue main sequence stars are

A

high mass.

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13
Q

High mass main sequence stars have

A

very short lives.

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14
Q

You observe a star cluster that contains blue main sequence stars. That cluster is most likely:

A

young.

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15
Q

You observe a star cluster that contains blue main sequence stars. That cluster is most likely:

A

young.

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16
Q

Our sun will not become a nova because

A

it does not have a binary companion.

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17
Q

Black holes are formed by

A

supernovae from the most massive stars.

18
Q

List, in the correct order, a possible evolutionary path for a star.

A

Red Giant, Planetary Nebula, White Dwarf.

19
Q

For a white dwarf to become a type II supernova it is necessary for it to

A

It cannot become a type II supernova.

20
Q

Red giant stars

A

have a very large radius.

21
Q

What kind of supernova was the Planet Express ship most likely way too close to when it exploded?

A

Type II.

22
Q

Light has no mass. According to Newton’s Law of Gravity, does light have gravity?

A

No.

23
Q

Light has no mass. According to Newton’s Law of Gravity, does light have gravity?

A

No.

24
Q

According to Newton’s Law of Gravity, can light be affected by a massive object?

A

No.

25
Q

If the Sun turned into a black hole, but kept the same mass as it has now, what would happen to the Earth’s orbit?

A

Nothing would change.

26
Q

If the Sun turned into a black hole, but kept the same mass as it has now, what would happen to the Earth’s orbit?

A

Nothing would change.

27
Q

You observe a massive star cluster that is only 1 million years old. Which spectral type of main sequence star would you expect to have run out of hydrogen in its core, evolved off of the main sequence, and thus be missing from the cluster’s HR diagram?

A

I would not expect any stars to have left the main sequence in this cluster.

28
Q

You begin an observing program to find all star clusters that are 1 billion years old. Which of the choices below lists the spectral types of the main sequence stars you would expect to find in a 1 billion year old cluster?

A

F, G, K, M.

29
Q

Which stars will eventually go through the red supergiant phase?

A

High mass stars.

30
Q

Which stars will eventually go through the red supergiant phase?

A

High mass stars.

31
Q

If you see a star cluster with red supergiants, that cluster has to be:

A

young.

32
Q

Stars with initial (main sequence) masses between about 0.5 and 8 times the mass of the Sun will eventually become white dwarfs. If you observe a star cluster that has white dwarfs, you can confidently say that the cluster is:

A

at least 100 million year old, but possibly older.

33
Q

You plot HR diagrams for two star clusters. Sandy has only a main sequence with stars that range from being very bright and hot to cool and faint. Patrick has a short main sequence with cool, faint stars, as well as red giants. Which cluster formed more recently?

A

Sandy.

34
Q

White dwarfs are the remnants of

A

lower mass stars.

35
Q

You observe two clusters, one has WDs and the other does not. Which one is older?

A

the one with WDs is older.

36
Q

You observe two clusters, one has WDs and the other does not. Which one is older?

A

the one with WDs is older.

37
Q

Which of the following best describes the behavior of the main sequence turn off (MSTO)?

A

the MSTO gets fainter as the cluster gets older

38
Q

Which of the following main sequence stars will become a red supergiant?

a) 0.5 solar mass
b) 1 solar mass
c) 5 solar mass
d) 15 solar mass

A

15 solar mass.

39
Q

The sun will go through what stages of stellar evolution?

A

MS, red giant, planetary nebula, white dwarf.

40
Q

The sun will go through what stages of stellar evolution?

A

MS, red giant, planetary nebula, white dwarf.

41
Q

A galaxy that appears to be populated by mostly red stars, likely:

A

had blue stars that are not present anymore but was present at some point in the past.

42
Q

Why are the arms of spiral galaxies typically blue in color?

A

Stars are forming in the spiral arms so there are high mass, hot, blue stars in the arms.

ASTR 1102 (1 decks)

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