Worksheet: Stellar Evolution

In this worksheet, we will practice describing how stars of different masses develop over the course of billions of years.

Q1:

List the following stages of stellar evolution in order for a certain star that has a mass of 80% of the Sun:

  1. A white dwarf
  2. A nebula
  3. A red giant
  4. A main sequence star
  5. A protostar
  • Ab, a, d, c, e
  • Bb, e, d, c, a
  • Cb, c, d, e, a
  • Db, e, c, d, a
  • Ed, e, b, c, a

Q2:

For approximately how long does a star like the Sun remain a main sequence star?

  • A100 million years
  • B100 billion years
  • C10 million years
  • D10 billion years
  • E1 trillion years

Q3:

Which of the following is the correct description of a black dwarf star?

  • AA black dwarf star is an extremely dense object that is made up only of neutrons.
  • BA black dwarf star is an object that has been left after a supernova in which all of the matter has been compressed into a single point. The gravitational field is so strong that not even light can escape.
  • CA black dwarf star is a type of star that is not massive enough to trigger nuclear fusion in its core, and so the only light it emits comes from its heat.
  • DA black dwarf star is a white dwarf star that has cooled so that it no longer emits any light.
  • EA black dwarf star is a type of star that only emits gamma radiation and does not emit any visible light.

Q4:

Which of the following is the correct description of a nebula?

  • AA nebula is a collection of billions of stars.
  • BA nebula is a dense object that is made up only of neutrons.
  • CA nebula is a collection of galaxies.
  • DA nebula is a cloud of gas and dust within a galaxy.
  • EA nebula is a fast-spinning neutron star.

Q5:

The diagram shows nine possible stages in the evolution of a star. For a star that will eventually become a neutron star, give the correct stages in the correct order, starting from a nebula.

  • A(i), (h), (d), (e), (a)
  • B(i), (h), (g), (e), (a)
  • C(i), (g), (h), (e), (a)
  • D(i), (b), (h), (e), (a)
  • E(i), (g), (h), (d), (a)

Q6:

The diagram shows six stages in the evolution of a star that has a mass similar to that of the Sun. What is the correct order of the stages?

  • A(e), (c), (d), (a), (f), (b)
  • B(e), (c), (d), (a), (b), (f)
  • C(e), (d), (c), (a), (b), (f)
  • D(e), (c), (d), (b), (a), (f)
  • E(f), (d), (c), (a), (b), (e)

Q7:

Which of the following is the correct description of a supernova?

  • AA supernova is a cataclysmic explosion that occurs when the core of a massive star collapses. Supernovas are so bright that they can outshine an entire galaxy for weeks.
  • BA supernova is a cataclysmic explosion that occurs when a black hole exceeds a mass 100 times that of the Sun.
  • CA supernova is a cataclysmic explosion that occurs when two galaxies collide.
  • DA supernova is a cataclysmic explosion that occurs when two neutron stars collide.
  • EA supernova is a cataclysmic explosion that occurs when a main sequence star like the Sun runs out of hydrogen to use for nuclear fusion.

Q8:

Alpha Orionis is a star in the constellation of Orion approximately 724 light-years away. Its mass is 12 times that of the Sun. Observations of Alpha Orionis suggest that it may explode as a supernova in less than 100,000 years. What type of a star is Alpha Orionis?

  • AA red giant
  • BA white dwarf star
  • CA main sequence star
  • DA red supergiant
  • EA neutron star

Q9:

The Sun is currently using hydrogen for nuclear fusion in its core. Eventually, it will run out of hydrogen while heavier elements, such as helium, will undergo fusion instead. This will cause the Sun to expand and become a red giant. What will happen after the Sun has run out of heavier elements that it uses for fusion?

  • AThe Sun will explode as a supernova. The outer layers of the Sun will be ejected and the core will become a black hole.
  • BThe Sun will explode as a supernova. The outer layers of the Sun will be ejected and the core will become a neutron star.
  • CNuclear fusion will stop in the core and because of its gravity, the Sun will collapse and become a white dwarf star.
  • DNuclear fusion will stop in the core and because of its gravity, the Sun will collapse and become a neutron star.
  • ENuclear fusion will stop in the core and because of its gravity, the Sun will collapse and become a black hole.

Q10:

The diagram shows nine possible stages in the evolution of a star. For a star that will eventually become a black hole, give the correct stages in the correct order, starting from a nebula.

  • A(e), (i), (h), (a), (b)
  • B(e), (i), (g), (a), (b)
  • C(e), (i), (a), (h), (b)
  • D(e), (f), (a), (c), (b)
  • E(e), (f), (a), (h), (b)

Q11:

Very large main sequence stars will eventually become red supergiants. Once a red supergiant has used up all of the material it can use for fusion, it will explode as a supernova. Depending on the original star’s mass, it will become one of two types of astronomical objects shown in the diagram. Which two types might the red supergiant become?

  • A(a) and (b)
  • B(a) and (c)
  • C(b) and (f)
  • D(a) and (f)
  • E(i) and (b)

Q12:

For a star that is much larger than the Sun, which of the following might it eventually become?

  • AA neutron star
  • BA black dwarf
  • CA brown dwarf
  • DA proton star
  • EA white dwarf

Q13:

What type of star is the Sun now?

  • AA neutron star
  • BA main sequence star
  • CA white dwarf star
  • DA red giant star
  • EA pulsar

Q14:

No black dwarf stars have ever been observed. Which of the following reasons explains why?

  • AThe number of white dwarf stars in the galaxy is very small; thus, the number of black dwarf stars is even smaller.
  • BThe amount of time it would take a white dwarf star to cool to become a black dwarf star is longer than the age of the universe; therefore, none are expected to exist yet.
  • CBlack dwarf stars are only expected to form in the galactic center. Since dust obscures our view of the galactic center, no black dwarf stars have ever been observed directly.
  • DBlack dwarf stars only emit gamma radiation, and we do not have gamma-ray telescopes with high enough resolution yet to be able to detect them.

Q15:

Which of the following is the correct description of a red giant star?

  • AA red giant star is a type of star that only produces light through heat. No fusion happens in the core of a red giant star.
  • BA red giant star is a star that has used up all of the hydrogen within it that was available to be used for nuclear fusion. The red giant star then starts to fuse heavier elements, such as helium, which produces less energy, and thus the star expands and cools.
  • CA red giant star is a type of star that only produces infrared light.
  • DA red giant star is a type of star that produces no ultraviolet light.

Q16:

Will the Sun become a red supergiant star? If not, why not?

  • ANo, because only binary stars become red supergiants.
  • BNo, because only stars in the early universe became red supergiants.
  • CYes
  • DNo, because only stars in the galactic center become red supergiants.
  • ENo, because it does not have a large enough mass.

Q17:

For a star that is about the same size as the Sun or smaller, which of the following will it eventually become?

  • AA red supergiant
  • BA white dwarf
  • CA neutron star
  • DA brown dwarf
  • EA black hole

Q18:

The Sun is a main sequence star. For stars that are about the same size as the Sun or smaller, what is the next stage in their stellar evolution?

  • AThey become black holes.
  • BThey expand to become red supergiants.
  • CThey expand to become red giants.
  • DThey explode as a supernova.
  • EThey become neutron stars.

Q19:

Which of the following is the correct description of a black hole?

  • AA black hole is an object that remains after a supernova in which all of the matter has been compressed into a single point. The gravitational field is so strong that not even light can escape.
  • BA black hole is an extremely dense object that remains after a supernova and is made up only of protons.
  • CA black hole is an extremely dense object that remains after a supernova and is made up only of neutrons.
  • DA black hole is an object which creates dark matter.
  • EA black hole is a white dwarf star that has cooled until it no longer emits any light.

Q20:

Which of the following is the correct description of a neutron star?

  • AA neutron star is an object that remains after a supernova in which all of the matter has been compressed into a single point.
  • BA neutron star is an extremely dense object that remains after a supernova and is made up only of neutrons.
  • CA neutron star is a type of star that emits high numbers of neutrons along its central axis.
  • DA neutron star is a type of star that has a net zero electric charge.
  • EA neutron star is a star that has ejected its outer layers, leaving behind a hot dense object made up of heavy elements.

Q21:

Which of the following is the correct description of a white dwarf star?

  • AA white dwarf star is an object that remains after a red giant star ejected its outer layers, leaving only a hot dense core.
  • BA white dwarf star is an extremely dense object that is made up only of neutrons.
  • CA white dwarf star is an object that creates energy and matter.
  • DA white dwarf star is a main sequence star that emits perfectly white light.
  • EA white dwarf star is an extremely dense object that is made up only of protons.

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