Astronomy 1010
Astronomy 1010 Final Exam Study
Guide 2025
Which two energy sources can help a star maintain its internal thermal pressure? -
Correct Answer ✔Nuclear fusion and gravitational contraction
What is the source of luminosity for protostars that have not yet become hot enough for
fusion in their cores? -Correct Answer ✔Gravitational energy released by infalling matter
What can we learn about a star from its life track on an H-R diagram? -Correct Answer
✔What surface temperature and luminosity it will have at each stage of life
Which of the following statements about degeneracy pressure is not true? -Correct
Answer ✔Degeneracy pressure varies with the temperature of the star
What percentage of a star's total lifetime is spent on the main sequence? -Correct
Answer ✔90%
What happens when a star like the sun exhausts its core hydrogen supply? -Correct
Answer ✔Its core contracts, but its outer layers expand and the star becomes bigger
and brighter
Helium fusion directly results in the formation of -Correct Answer ✔Carbon
What happens after the helium flash in the core of a star? -Correct Answer ✔The core
quickly heats up and expands as helium fusion begins all at once throughout the core
Which of the following sequences correctly describes the stages of life for a one solar
mass star? -Correct Answer ✔Protostar, main-sequence, red giant, white dwarf
What is the CNO cycle? -Correct Answer ✔a type of hydrogen fusion that uses carbon,
nitrogen, and oxygen nuclei as catalysts
Why does stellar main-sequence lifetime decrease with increasing stellar mass? -
Correct Answer ✔Higher core temperatures cause fusion to proceed much more rapidly
Which element has the lowest mass per nuclear particle and therefore cannot release
energy by either fusion or fission? -Correct Answer ✔Iron
What happens when the gravity of a massive star's collapsing core is able to overcome
neutron degeneracy pressure? -Correct Answer ✔The core contracts and becomes a
black hole
Astronomy 1010
, Astronomy 1010
Which of the following statements about the stages of nuclear burning in a massive star
is not true? -Correct Answer ✔Each successive stage lasts for approximately as long as
the first, hydrogen fusion stage.
Which event marks the beginning of a supernova? -Correct Answer ✔The sudden
collapse of an iron core into a compact ball of neutrons
You discover a binary star system in which one member is a 15 solar mass main-
sequence star and the other star is a 10 solar mass giant star. Why should you be
surprised, at least at first? -Correct Answer ✔The two stars should be the same age, so
the more massive one should have become a giant first
Consider a large molecular cloud that will give birth to a cluster of stars. Which of the
following would you expect to be true? -Correct Answer ✔A few massive stars will form,
live, and die before the majority of the star's clusters even complete their protostar
stage.
This diagram represents the life track of a 1 solar mass star. Refer to the life stages
labeled with roman numerals. Which stage lasts the longest? -Correct Answer ✔Main
sequence line
Carbon fusion occurs in high-mass stars but not in low-mass stars because... -Correct
Answer ✔The cores of low-mass stars never get hot enough for carbon fusion
A spinning neutron star has been observed at the center of a -Correct Answer
✔Supernova remnant
Degeneracy pressure stops the crush of gravity in all the following except -Correct
Answer ✔A very massive main-sequence star
Suppose a white dwarf is gaining mass because of accretion from a binary companion.
What happens if its mass reaches the 1.4 solar mass limit? -Correct Answer
✔Temperatures skyrocket to the point where carbon fusion is possible, which leads to a
white dwarf supernova explosion
Which of the following statements about novae is not true? -Correct Answer ✔Our Sun
will probably undergo at least one nova when it becomes a white dwarf about 5 billion
years from now
What kind of star is most likely to become a white-dwarf supernova? -Correct Answer
✔A white dwarf star with a red giant binary companion
From an observational standpoint, what is a pulsar? -Correct Answer ✔An object that
emits flashes of light several times per second, with near perfect regularity
Astronomy 1010
Astronomy 1010 Final Exam Study
Guide 2025
Which two energy sources can help a star maintain its internal thermal pressure? -
Correct Answer ✔Nuclear fusion and gravitational contraction
What is the source of luminosity for protostars that have not yet become hot enough for
fusion in their cores? -Correct Answer ✔Gravitational energy released by infalling matter
What can we learn about a star from its life track on an H-R diagram? -Correct Answer
✔What surface temperature and luminosity it will have at each stage of life
Which of the following statements about degeneracy pressure is not true? -Correct
Answer ✔Degeneracy pressure varies with the temperature of the star
What percentage of a star's total lifetime is spent on the main sequence? -Correct
Answer ✔90%
What happens when a star like the sun exhausts its core hydrogen supply? -Correct
Answer ✔Its core contracts, but its outer layers expand and the star becomes bigger
and brighter
Helium fusion directly results in the formation of -Correct Answer ✔Carbon
What happens after the helium flash in the core of a star? -Correct Answer ✔The core
quickly heats up and expands as helium fusion begins all at once throughout the core
Which of the following sequences correctly describes the stages of life for a one solar
mass star? -Correct Answer ✔Protostar, main-sequence, red giant, white dwarf
What is the CNO cycle? -Correct Answer ✔a type of hydrogen fusion that uses carbon,
nitrogen, and oxygen nuclei as catalysts
Why does stellar main-sequence lifetime decrease with increasing stellar mass? -
Correct Answer ✔Higher core temperatures cause fusion to proceed much more rapidly
Which element has the lowest mass per nuclear particle and therefore cannot release
energy by either fusion or fission? -Correct Answer ✔Iron
What happens when the gravity of a massive star's collapsing core is able to overcome
neutron degeneracy pressure? -Correct Answer ✔The core contracts and becomes a
black hole
Astronomy 1010
, Astronomy 1010
Which of the following statements about the stages of nuclear burning in a massive star
is not true? -Correct Answer ✔Each successive stage lasts for approximately as long as
the first, hydrogen fusion stage.
Which event marks the beginning of a supernova? -Correct Answer ✔The sudden
collapse of an iron core into a compact ball of neutrons
You discover a binary star system in which one member is a 15 solar mass main-
sequence star and the other star is a 10 solar mass giant star. Why should you be
surprised, at least at first? -Correct Answer ✔The two stars should be the same age, so
the more massive one should have become a giant first
Consider a large molecular cloud that will give birth to a cluster of stars. Which of the
following would you expect to be true? -Correct Answer ✔A few massive stars will form,
live, and die before the majority of the star's clusters even complete their protostar
stage.
This diagram represents the life track of a 1 solar mass star. Refer to the life stages
labeled with roman numerals. Which stage lasts the longest? -Correct Answer ✔Main
sequence line
Carbon fusion occurs in high-mass stars but not in low-mass stars because... -Correct
Answer ✔The cores of low-mass stars never get hot enough for carbon fusion
A spinning neutron star has been observed at the center of a -Correct Answer
✔Supernova remnant
Degeneracy pressure stops the crush of gravity in all the following except -Correct
Answer ✔A very massive main-sequence star
Suppose a white dwarf is gaining mass because of accretion from a binary companion.
What happens if its mass reaches the 1.4 solar mass limit? -Correct Answer
✔Temperatures skyrocket to the point where carbon fusion is possible, which leads to a
white dwarf supernova explosion
Which of the following statements about novae is not true? -Correct Answer ✔Our Sun
will probably undergo at least one nova when it becomes a white dwarf about 5 billion
years from now
What kind of star is most likely to become a white-dwarf supernova? -Correct Answer
✔A white dwarf star with a red giant binary companion
From an observational standpoint, what is a pulsar? -Correct Answer ✔An object that
emits flashes of light several times per second, with near perfect regularity
Astronomy 1010
