Question 1

This diagram represents the life track of a 1-solar-mass star.Refer to the life stages labeled with Roman numerals.
 
-During which stage does the star have an inert (non-burning)helium core?

Accepted Answer

During stage IV, a star has an inert helium core. This occurs after the hydrogen in the core has been exhausted and before helium fusion begins.

Question 2

You discover a binary star system in which one star is a 15 MSᵤn main-sequence star and the other is a 10 MSᵤn giant.How do we think that a star system such as this might have come to exist?

Accepted Answer

The giant star must have once been the more massive one, but it transferred some of its mass to its companion, causing the current mass difference between the two stars. This is known as mass transfer.

Question 3

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?

Accepted Answer

Stage III, also known as the interphase, is the longest phase of the cell cycle, where the cell prepares for division by growing and replicating its DNA.

Question 4

A spinning neutron star has been observed at the center of a

Accepted Answer

A spinning neutron star is a type of pulsar, which is often found at the center of a supernova remnant. This is because pulsars are created from the collapsed core of a massive star that has undergone a supernova explosion.

Question 5

Which of the following types of data provide evidence that helps us understand the life tracks of low-mass stars?

Accepted Answer

The answer of Which of the following types of data...

Question 6

This diagram represents the life track of a 1-solar-mass star.Refer to the life stages labeled with Roman numerals.
 
-What will happen to the star after stage VIII?

Accepted Answer

After stage VIII, the star will enter the asymptotic giant branch (AGB) phase, during which it will expand and cool down. Eventually, the outer layers of the star will be ejected as a planetary nebula, leaving behind a hot, dense core that will become a white dwarf. This is the fate of low- to intermediate-mass stars like the one depicted in the diagram. Options B and C are not applicable to this type of star, and option D is incorrect because stage VIII (the red giant phase) only lasts a few hundred million years, not 10 billion years.

Question 7

Which of the following describes a star with a hydrogen-burning shell and an inert helium core?

Accepted Answer

This description matches a subgiant star, which increases in brightness as it evolves and expands, with a hydrogen-burning shell surrounding an inert helium core, until helium fusion ignites in the core.

Question 8

Where does gold (the element)come from?

Accepted Answer

Gold is believed to be produced during the supernova explosions of high-mass stars. During these explosions, the intense pressure and temperature cause the fusion of atomic nuclei, leading to the creation of heavier elements like gold.

Question 9

Which of the following observations would not be likely to provide information about the final,explosive stages of a star's life?

Accepted Answer

Red giants in globular clusters are not typically associated with the final, explosive stages of a star's life. They are stars that have already undergone significant evolution and are in a later stage of their lives. Therefore, monitoring them for decades would not provide information on the explosive final stages of a star's life. The other options, studying Supernova 1987A, observing planetary nebulae, and detecting neutrinos from nearby supernovae, all provide information about the final, explosive stages of a star's life.

Question 10

Suppose that hydrogen,rather than iron,had the lowest mass per nuclear particle.Which of the following would be true?

Accepted Answer

If hydrogen had the lowest mass per nuclear particle, it would mean that fusing hydrogen into heavier elements would not release energy, as is the case in our universe where fusion up to iron releases energy. This energy release is what powers stars. Without this energy release from fusion, nuclear fusion could not serve as the power source for stars.

Question 11

Sun is considered to be a

Accepted Answer

The mass of the Sun is approximately 1.989 x 10^30 kilograms, which falls within the range of low-mass stars. High-mass stars are typically greater than 3 solar masses, intermediate-mass stars range from 1.5 to 3 solar masses, and brown dwarfs are sub-stellar objects with masses between 13 and 80 Jupiter masses.

Question 12

Which of the following statements about various stages of core nuclear burning (hydrogen,helium,carbon,etc. )in a high-mass star is not true?

Accepted Answer

Each successive stage lasts for a shorter amount of time than the previous stage, as the rate of fusion reactions increases with the increasing temperature and pressure in the core.

Question 13

Which event marks the beginning of a supernova?

Accepted Answer

The sudden collapse of an iron core into a compact ball of neutrons marks the beginning of a supernova. This collapse creates a shockwave that causes the outer layers of the star to explode in a massive explosion.

Question 14

Why is a 1 solar-mass red giant more luminous than a 1 solar-mass main-sequence star?

Accepted Answer

The red giant is more luminous because fusion reactions are producing energy at a greater rate in the red giant than in a main-sequence star. As the red giant has exhausted the hydrogen fuel in its core and fusion now occurs in a shell around the core where compression and temperature are higher. This makes the red giant brighter and more luminous than a main-sequence star of the same mass.

Question 15

Which is more common: a star blows up as a supernova,or a star forms a planetary nebula/white dwarf system?

Accepted Answer

Planetary nebula formation is more common than supernovae. Many stars, especially low-mass stars like the Sun, will eventually form planetary nebulae and white dwarfs as they near the end of their lives. Supernovae occur much less frequently, typically only in very massive stars.

Question 16

Observations show that elements with atomic mass numbers divisible by 4 (such as oxygen-16,neon-20,and magnesium-24)tend to be more abundant in the universe than elements with atomic mass numbers in between.Why do we think this is the case?

Accepted Answer

High-mass stars produce elements through helium capture reactions, which often result in elements with atomic mass numbers divisible by 4, making them more abundant.

Question 17

Suppose that the star Betelgeuse (the upper left shoulder of Orion)were to supernova tomorrow (as seen here on Earth).What would it look like to the naked eye?

Accepted Answer

Betelgeuse, if it were to supernova, would indeed become significantly brighter, but it would still appear as a point of light to the naked eye. Its brightness could increase to the point where it would be visible during the daytime for a period. Supernovae do not cause stars to visually expand to the size of the Moon to the naked eye, nor do they result in the immediate visible expansion of a gas cloud or the star disappearing instantly.

Question 18

This diagram represents the life track of a 1-solar-mass star.Refer to the life stages labeled with Roman numerals.
 
-During which stage is the star's energy supplied by primarily by gravitational contraction?

Accepted Answer

The energy during stage II (protostar) is primarily supplied by gravitational contraction as the star is still forming and has not yet begun nuclear fusion.

Question 19

Carbon fusion occur in high-mass stars but not in low-mass stars because

Accepted Answer

Low-mass stars do not have enough gravitational pressure in their cores to reach the high temperatures required for carbon fusion.

Question 20

This diagram represents the life track of a 1-solar-mass star.Refer to the life stages labeled with Roman numerals.
 
-During which stage does the star have an inert (non-burning)carbon core surrounded by shells of helium and hydrogen burning?

Accepted Answer

In stage VIII, a star has an inert carbon core with surrounding shells of helium and hydrogen burning. This stage occurs after the helium burning phase in the core has ended, leading to the formation of a carbon core.

Quiz 17: Star Stuff

This diagram represents the life track of a 1-solar-mass star.Refer to the life stages labeled with Roman numerals. -During which stage does the star have an inert (non-burning) helium core?

You discover a binary star system in which one star is a 15 MSᵤn main-sequence star and the other is a 10 MSᵤn giant.How do we think that a star system such as this might have come to exist?

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?

A spinning neutron star has been observed at the center of a

Which of the following types of data provide evidence that helps us understand the life tracks of low-mass stars?

This diagram represents the life track of a 1-solar-mass star.Refer to the life stages labeled with Roman numerals. -What will happen to the star after stage VIII?

Which of the following describes a star with a hydrogen-burning shell and an inert helium core?

Where does gold (the element) come from?

Which of the following observations would not be likely to provide information about the final,explosive stages of a star's life?

Suppose that hydrogen,rather than iron,had the lowest mass per nuclear particle.Which of the following would be true?

Sun is considered to be a

Which of the following statements about various stages of core nuclear burning (hydrogen,helium,carbon,etc. ) in a high-mass star is not true?

Which event marks the beginning of a supernova?

Why is a 1 solar-mass red giant more luminous than a 1 solar-mass main-sequence star?

Which is more common: a star blows up as a supernova,or a star forms a planetary nebula/white dwarf system?

Observations show that elements with atomic mass numbers divisible by 4 (such as oxygen-16,neon-20,and magnesium-24) tend to be more abundant in the universe than elements with atomic mass numbers in between.Why do we think this is the case?

Suppose that the star Betelgeuse (the upper left shoulder of Orion) were to supernova tomorrow (as seen here on Earth) .What would it look like to the naked eye?

This diagram represents the life track of a 1-solar-mass star.Refer to the life stages labeled with Roman numerals. -During which stage is the star's energy supplied by primarily by gravitational contraction?

Carbon fusion occur in high-mass stars but not in low-mass stars because

This diagram represents the life track of a 1-solar-mass star.Refer to the life stages labeled with Roman numerals. -During which stage does the star have an inert (non-burning) carbon core surrounded by shells of helium and hydrogen burning?