Astronomy A Beginners Guide To The Universe 7th Edition By Chaisson – Test Bank

Astronomy A Beginners Guide To The Universe 7th Edition by Chaisson – Test Bank

Astronomy: A Beginner’s Guide to the Universe, 7e (Chaisson/McMillan)

Chapter 12   Stellar Evolution: The Lives and Deaths of Stars

 1) As a main-sequence star, the Sun’s hydrogen supply should last about 10 billion years from the zero-age main sequence until its evolution to the giant stages.

Answer:  TRUE

Diff: 1

Section Ref.:  12.1

2) About 90% of the star’s total life is spent on the main sequence.

Answer:  TRUE

Diff: 1

Section Ref.:  12.1

3) Helium fusion requires a higher temperature than hydrogen fusion.

Answer:  TRUE

Diff: 1

Section Ref.:  12.2

4) While more massive than most of its neighbors, our Sun is still technically a low-mass star.

Answer:  TRUE

Diff: 1

Section Ref.:  12.1

5) The least massive red main-sequence stars may have lifetimes of a trillion years.

Answer:  TRUE

Diff: 2

Section Ref.:  12.1

6) The main reason that stars evolved off the main sequence is because they are becoming less massive as energy is lost into space from the proton-proton cycle.

Answer:  FALSE

Diff: 2

Section Ref.:  12.1

7) The initial rise off the main sequence in stage 8 comes from gravitational energy of the contracting helium core.

Answer:  TRUE

Diff: 2

Section Ref.:  12.2

8) Paradoxically, while the core of the red giant is contracting and heating up, its radiation pressure causes its photosphere to swell up and cool off.

Answer:  TRUE

Diff: 2

Section Ref.:  12.2

9) Once the helium flash occurs at stage 10, the star stabilizes again on the horizontal branch of the H-R diagram, but now hundreds of times as bright as on the main sequence.

Answer:  TRUE

Diff: 2

Section Ref.:  12.2

10) The helium flash stage lasts several thousand years.

Answer:  FALSE

Diff: 2

Section Ref.:  12.2

11) The helium flash increases the star’s luminosity.

Answer:  FALSE

Diff: 2

Section Ref.:  12.2

12) The luminosity of the red giant during its second trip to the upper right on the H-R diagram is less than before the helium flash expansion.

Answer:  FALSE

Diff: 2

Section Ref.:  12.2

13) A star may undergo two or more red giant expansion stages.

Answer:  TRUE

Diff: 2

Section Ref.:  12.2

14) The helium flash shows up on the H-R diagram on the way to the horizontal branch.

Answer:  TRUE

Diff: 2

Section Ref.:  12.2

15) Our Sun will fade in luminosity as its supply of hydrogen drops in a billion years.

Answer:  FALSE

Diff: 2

Section Ref.:  12.2

16) A typical star burns helium for about the same amount of time it burns hydrogen.

Answer:  FALSE

Diff: 2

Section Ref.:  12.2

17) Low-mass stars may become hundreds of times more luminous as giants than they were on the main sequence.

Answer:  TRUE

Diff: 2

Section Ref.:  12.2

18) All stars have roughly the same luminosity after the helium flash.

Answer:  TRUE

Diff: 2

Section Ref.:  12.2

19) Our Sun should become a planetary nebula in another five billion years.

Answer:  TRUE

Diff: 1

Section Ref.:  12.3

20) A star system may undergo two or more nova outbursts.

Answer:  TRUE

Diff: 1

Section Ref.:  12.3

21) Our Sun will eventually become a nova.

Answer:  FALSE

Diff: 2

Section Ref.:  12.3

22) Our Sun will never become hot enough for carbon nuclei to fuse.

Answer:  TRUE

Diff: 2

Section Ref.:  12.3

23) The density of white dwarf stars is about a million times that of the Sun.

Answer:  TRUE

Diff: 2

Section Ref.:  12.3

24) The nova event is created by the helium flash.

Answer:  FALSE

Diff: 2

Section Ref.:  12.3

25) Today the majority of the mass of the universe is already in the form of black dwarfs, the solution to the “dark matter” problem.

Answer:  FALSE

Diff: 3

Section Ref.:  12.3

26) Our Sun will first become a red giant, then a white dwarf, and finally a brown dwarf.

Answer:  FALSE

Diff: 2

Section Ref.:  12.3

27) As their name implies, all planetary nebulae feature spherical shells and look like the disks of Uranus or Neptune.

Answer:  FALSE

Diff: 2

Section Ref.:  12.3

28) While there are none yet, in the very distant future, most normal matter will be in the form of black dwarfs.

Answer:  TRUE

Diff: 3

Section Ref.:  12.3

29) Compared to the interstellar medium, the gases in a planetary nebula will be richer in helium and carbon.

Answer:  TRUE

Diff: 2

Section Ref.:  12.3

30) Like emission nebulae, planetary nebulae glow because hot stars are causing the gases to ionize when exposed to strong ultraviolet radiation.

Answer:  TRUE

Diff: 2

Section Ref.:  12.3

31) Although mass transfer can occur in binary stars, the small mass change does not impact the evolution of either companion.

Answer:  FALSE

Diff: 2

Section Ref.:  12.3

32) A white dwarf’s atoms have their electron orbitals crushed as closely as the Exclusion Principle allows.

Answer:  TRUE

Diff: 2

Section Ref.:  12.3

33) White dwarfs were once the cores of stars that produced planetary nebulae.

Answer:  TRUE

Diff: 2

Section Ref.:  12.3

34) Solar mass stars eventually become hot enough for carbon nuclei to fuse together.

Answer:  FALSE

Diff: 2

Section Ref.:  12.3

35) It is the formation of iron in an evolved giant’s core that triggers a Type II supernova event.

Answer:  TRUE

Diff: 1

Section Ref.:  12.4

36) In the cores of the most massive stars, the electrons and protons fuse together and form neutrons.

Answer:  FALSE

Diff: 2

Section Ref.:  12.4

37) Elements heavier than iron are formed mainly in supernovae.

Answer:  TRUE

Diff: 2

Section Ref.:  12.4

38) Only low mass stars experience the temporary instability of the helium flash; high mass stars go directly into heavier element formation.

Answer:  TRUE

Diff: 2

Section Ref.:  12.4

39) A massive star may change its color and size notably, but its high luminosity remains fairly constant.

Answer:  TRUE

Diff: 2

Section Ref.:  12.4

40) The formation of carbon requires a core temperature of about 100 million K, but iron takes much higher temperatures and pressures.

Answer:  TRUE

Diff: 2

Section Ref.:  12.4

41) Supergiant stars are burning different fuels in several shells around the core.

Answer:  TRUE

Diff: 2

Section Ref.:  12.4

42) Our Sun will likely die as a Type I supernova in about five billion years.

Answer:  FALSE

Diff: 1

Section Ref.:  12.5

43) A star system can become a Type I supernova several times.

Answer:  FALSE

Diff: 1

Section Ref.:  12.5

44) A massive star can fuse only up to the element silicon in its core.

Answer:  FALSE

Diff: 1

Section Ref.:  12.5

45) The helium flash is followed within a few million years by the Type II supernova.

Answer:  FALSE

Diff: 2

Section Ref.:  12.5

46) Supernova 1987A was the first supernova observed by astronomers since Galileo first turned a telescope to the heavens.

Answer:  TRUE

Diff: 2

Section Ref.:  Disc. 12.1

47) While luminous enough to be seen with the naked eye, Supernova 1987A was, in fact, in our companion galaxy, the Large Magellanic Cloud.

Answer:  TRUE

Diff: 2

Section Ref.:  Disc. 12.1

48) Gold is rare since the only time it can be formed is during the core collapse of a supernova.

Answer:  TRUE

Diff: 2

Section Ref.:  12.5

49) Chandrasekhar’s limit is 1.4 times the mass of our Sun.

Answer:  TRUE

Diff: 2

Section Ref.:  12.5

50) Because they all involve formation of iron in the cores of massive stars, all Type II supernovae are approximately equally luminous.

Answer:  FALSE

Diff: 2

Section Ref.:  12.5