Question 1

During the first red giant phase, the source of a star's energy is:

Accepted Answer

A) shell hydrogen fusion only. 
B) both shell hydrogen fusion and core helium fusion. 
C) core helium fusion only. 
D) the Kelvin-Helmholtz contraction. 
A) shell hydrogen fusion only. 
B) both shell hydrogen fusion and core helium fusion. 
C) core helium fusion only. 
D) the Kelvin-Helmholtz contraction.

Question 2

In 1990, the HST first examined SN 1987A and found a ring of glowing gas surrounding it. In 1994, HST found three rings of glowing gas. What happened during this interval?

Accepted Answer

A) The core of SN 1987A bounced not once but twice, producing two additional rings. 
B) Radioactivity in the original ring heated it and caused it to expand and split. 
C) The shock wave from SN 1987A triggered the formation of planetary nebulae in two nearby stars. 
D) The optics on HST were repaired, resulting in better resolution. 
A) The core of SN 1987A bounced not once but twice, producing two additional rings. 
B) Radioactivity in the original ring heated it and caused it to expand and split. 
C) The shock wave from SN 1987A triggered the formation of planetary nebulae in two nearby stars. 
D) The optics on HST were repaired, resulting in better resolution.

Question 3

Very heavy elements beyond iron in the periodic table are formed in the interiors of massive stars by what process in general?

Accepted Answer

A) triple alpha process 
B) neutron capture 
C) splitting of heavier elements by nuclear fission 
D) CNO cycle of nuclear fusion 
A) triple alpha process 
B) neutron capture 
C) splitting of heavier elements by nuclear fission 
D) CNO cycle of nuclear fusion

Question 4

A planetary nebula is created:

Accepted Answer

A) over several hundred years, during mass transfer in a close binary star system. 
B) in seconds, during the helium flash in a low-mass star. 
C) slowly over 10,000 years or more, due to thermal pulses in a low-mass star. 
D) in hours or less, during the explosion of a massive star. 
A) over several hundred years, during mass transfer in a close binary star system. 
B) in seconds, during the helium flash in a low-mass star. 
C) slowly over 10,000 years or more, due to thermal pulses in a low-mass star. 
D) in hours or less, during the explosion of a massive star.

Question 5

A white dwarf star, as it evolves, undergoes which of the following changes?

Accepted Answer

A) Luminosity and size decrease, while its temperature remains constant. 
B) Its temperature remains constant, but its radius and luminosity decrease. 
C) It shrinks in size, the resulting release of gravitational energy maintaining both luminosity and temperature constant. 
D) Luminosity and temperature decrease, but its size remains constant. 
A) Luminosity and size decrease, while its temperature remains constant. 
B) Its temperature remains constant, but its radius and luminosity decrease. 
C) It shrinks in size, the resulting release of gravitational energy maintaining both luminosity and temperature constant. 
D) Luminosity and temperature decrease, but its size remains constant.

Question 6

A supernova of Type Ia has a much higher peak luminosity than a supernova of Type II. When we measure luminosity, we are including the energy of all of the following EXCEPT:

Accepted Answer

A) ultraviolet radiation. 
B) gamma rays. 
C) neutrinos. 
D) x rays. 
A) ultraviolet radiation. 
B) gamma rays. 
C) neutrinos. 
D) x rays.

Question 7

When the small but dense white dwarf is formed from a star like the Sun, the core temperature is not high enough to permit the carbon and oxygen to participate in further energy-producing nuclear reactions. But why does this dense core not produce energy by the Kelvin-Helmholtz contraction?

Accepted Answer

A) Electron degeneracy holds up the star and prohibits contraction. 
B) Neutron degeneracy holds up the star and prohibits contraction. 
C) The Kelvin-Helmholtz contraction only applies to hydrogen. 
D) The Kelvin-Helmholtz contraction only applies to hydrogen and helium, not to metals. 
A) Electron degeneracy holds up the star and prohibits contraction. 
B) Neutron degeneracy holds up the star and prohibits contraction. 
C) The Kelvin-Helmholtz contraction only applies to hydrogen. 
D) The Kelvin-Helmholtz contraction only applies to hydrogen and helium, not to metals.

Question 8

A "carbon star" has more carbon on its surface than does the Sun. This is the result of:

Accepted Answer

A) neutrinos, which escape easily from the core of a star but react with the cool hydrogen at its surface to form carbon. 
B) helium flash, in which the explosion blasts carbon from the core into the surface layers. 
C) dredge-up, in which the convective envelope transports material from a star's core to its surface. 
D) mass loss, which strips away the outer envelope from an old star and reveals the carbon-rich core. 
A) neutrinos, which escape easily from the core of a star but react with the cool hydrogen at its surface to form carbon. 
B) helium flash, in which the explosion blasts carbon from the core into the surface layers. 
C) dredge-up, in which the convective envelope transports material from a star's core to its surface. 
D) mass loss, which strips away the outer envelope from an old star and reveals the carbon-rich core.

Question 9

When an iron core is formed in a massive star, what ultimately keeps the core from collapsing to form a black hole?

Accepted Answer

A) the pressure generated by fusion reactions within the iron core 
B) electron degeneracy 
C) neutron degeneracy 
D) Nothing; the iron core must collapse all the way to a black hole. 
A) the pressure generated by fusion reactions within the iron core 
B) electron degeneracy 
C) neutron degeneracy 
D) Nothing; the iron core must collapse all the way to a black hole.

Question 10

It is now thought that most elements in the universe heavier than iron in the periodic table:

Accepted Answer

A) are produced by the nuclear reactions in the central cores of high-mass stars a few hundred years before the star explodes into a supernova. 
B) were produced in the Big Bang explosion at the beginning of our universe. 
C) are produced by the successive capture of high-speed neutrons within low-mass star cores because neutrons are uncharged and can approach other nuclei without electrostatic repulsion. 
D) are produced by nuclear reactions in the shock wave regions surrounding supernova explosions. 
A) are produced by the nuclear reactions in the central cores of high-mass stars a few hundred years before the star explodes into a supernova. 
B) were produced in the Big Bang explosion at the beginning of our universe. 
C) are produced by the successive capture of high-speed neutrons within low-mass star cores because neutrons are uncharged and can approach other nuclei without electrostatic repulsion. 
D) are produced by nuclear reactions in the shock wave regions surrounding supernova explosions.

Question 11

Supergiants are huge stars of 25 or 30 M ? , which are undergoing core nuclear fusion involving nuclei heavier than carbon. These supergiants:

Accepted Answer

A) are always red. 
B) are always blue. 
C) are always white. 
D) may be any of a variety of colors. 
A) are always red. 
B) are always blue. 
C) are always white. 
D) may be any of a variety of colors.

Question 12

During which phase in the life of a solar mass star does helium shell burning occur?

Accepted Answer

A) first red giant phase 
B) main sequence 
C) horizontal branch 
D) asymptotic giant branch 
A) first red giant phase 
B) main sequence 
C) horizontal branch 
D) asymptotic giant branch

Question 13

The typical diameter of a planetary nebula is:

Accepted Answer

A) about 1000 ly. 
B) about 1 au. 
C) about 3 to 5 stellar diameters. 
D) about 1 ly. 
A) about 1000 ly. 
B) about 1 au. 
C) about 3 to 5 stellar diameters. 
D) about 1 ly.

Question 14

Supernova remnants are LEAST likely to be discovered when observers are attempting to detect them by looking for:

Accepted Answer

A) radio waves. 
B) x rays. 
C) visible light. 
D) neutrinos. 
A) radio waves. 
B) x rays. 
C) visible light. 
D) neutrinos.

Question 15

The shell of a planetary nebula is measured by the Doppler shift of emission lines to be expanding outward at a speed of 10 km/s and its diameter is measured to be 1 ly. How long has the shell been expanding?

Accepted Answer

A) 50,000 years 
B) 50 million years 
C) 50 years 
D) 9.5 × 1011 years 
A) 50,000 years 
B) 50 million years 
C) 50 years 
D) 9.5 × 1011 years

Question 16

More supernovae have been recorded, on average, in distant galaxies than in the Milky Way Galaxy. Why is this?

Accepted Answer

A) The Milky Way is a relatively small galaxy, so we would expect fewer supernovae. 
B) We can only view our own galaxy's central plane from within that plane, where dust obscures our view. We view other galaxies from a variety of orientations, not just along the central plane. 
C) The Milky Way is a particularly old galaxy, and the production rate of supernovae has decreased. 
D) Much of the radiation emitted from supernovae is not visible. The radiation from other galaxies, however, is often Doppler shifted into the visible, where it is more easily detected. 
A) The Milky Way is a relatively small galaxy, so we would expect fewer supernovae. 
B) We can only view our own galaxy's central plane from within that plane, where dust obscures our view. We view other galaxies from a variety of orientations, not just along the central plane. 
C) The Milky Way is a particularly old galaxy, and the production rate of supernovae has decreased. 
D) Much of the radiation emitted from supernovae is not visible. The radiation from other galaxies, however, is often Doppler shifted into the visible, where it is more easily detected.

Question 17

White dwarf stars of different masses have radii or sizes for which the:

Accepted Answer

A) more massive the star, the larger it is. 
B) sizes are the same for all stellar masses. 
C) sizes start out the same for all masses, but the more massive stars shrink fastest. 
D) more massive the star, the smaller it is. 
A) more massive the star, the larger it is. 
B) sizes are the same for all stellar masses. 
C) sizes start out the same for all masses, but the more massive stars shrink fastest. 
D) more massive the star, the smaller it is.

Question 18

One particular characteristic of a white dwarf star is its:

Accepted Answer

A) very high surface temperature. 
B) extremely low mass for a star, about 1/100 of 1 M ? 
C) very low surface temperature, because it is at the end of its life. 
D) spectrum, consisting simply of emission lines from hydrogen, helium, carbon, and oxygen. 
A) very high surface temperature. 
B) extremely low mass for a star, about 1/100 of 1 M ? 
C) very low surface temperature, because it is at the end of its life. 
D) spectrum, consisting simply of emission lines from hydrogen, helium, carbon, and oxygen.

Exam 20: Stellar Evolution: The Death of Stars

During the first red giant phase, the source of a star's energy is:

In 1990, the HST first examined SN 1987A and found a ring of glowing gas surrounding it. In 1994, HST found three rings of glowing gas. What happened during this interval?

Very heavy elements beyond iron in the periodic table are formed in the interiors of massive stars by what process in general?

A planetary nebula is created:

A white dwarf star, as it evolves, undergoes which of the following changes?

A supernova of Type Ia has a much higher peak luminosity than a supernova of Type II. When we measure luminosity, we are including the energy of all of the following EXCEPT:

When the small but dense white dwarf is formed from a star like the Sun, the core temperature is not high enough to permit the carbon and oxygen to participate in further energy-producing nuclear reactions. But why does this dense core not produce energy by the Kelvin-Helmholtz contraction?

A "carbon star" has more carbon on its surface than does the Sun. This is the result of:

When an iron core is formed in a massive star, what ultimately keeps the core from collapsing to form a black hole?

It is now thought that most elements in the universe heavier than iron in the periodic table:

Supergiants are huge stars of 25 or 30 M ? , which are undergoing core nuclear fusion involving nuclei heavier than carbon. These supergiants:

During which phase in the life of a solar mass star does helium shell burning occur?

The typical diameter of a planetary nebula is:

Supernova remnants are LEAST likely to be discovered when observers are attempting to detect them by looking for:

The shell of a planetary nebula is measured by the Doppler shift of emission lines to be expanding outward at a speed of 10 km/s and its diameter is measured to be 1 ly. How long has the shell been expanding?

More supernovae have been recorded, on average, in distant galaxies than in the Milky Way Galaxy. Why is this?

White dwarf stars of different masses have radii or sizes for which the:

One particular characteristic of a white dwarf star is its:

Astronomy and the Universe

Knowing the Heavens

Eclipses and the Motion of the Moon

Gravitation and the Waltz of the Planets

The Nature of Light

Optics and Telescopes

Comparative Planetology I: Our Solar System

Comparative Planetology II: the Origin of Our Solar System

The Living Earth

Our Barren Moon

Mercury, Venus, and Mars: Terrestrial, yet Unique

Jupiter and Saturn: Lords of the Planets

Jupiter and Saturns Satellites of Fire and Ice

Uranus, Neptune, Pluto, and the Kuiper Belt: Remote Worlds

Asteroids, Comets, and Impacts

Our Star, the Sun

The Nature of the Stars

The Birth of Stars

Stellar Evolution: on and After the Main Sequence

Stellar Remnants: Neutron Stars and Black Holes

Our Galaxy

Galaxies

Quasars and Active Galaxies

Cosmology: The Origin and Evolution of the Universe

Exploring the Early Universe

The Search for Extraterrestrial Life

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