Question 1

Which of the following is closest in size (radius)to a neutron star?

Accepted Answer

A) Earth 
B) a city 
C) a football stadium 
D) a basketball 
E) the Sun 
A) Earth 
B) a city 
C) a football stadium 
D) a basketball 
E) the Sun

Question 2

An advanced civilization lives on a planet orbiting a close binary star system that consists of a 15MSᵤn red giant and a 10MSᵤn black hole.Assume that the two stars are quite close together,so that an accretion disk surrounds the black hole.The planet on which the civilization lives orbits the binary star at a distance of 10 AU.
-Sometime within the next million years or so,their planet is likely to be doomed because

Accepted Answer

A) jets of material shot out of the accretion disk will shoot down their planet. 
B) their planet receives most of its energy from the red giant.However,this star will soon be completely devoured in the accretion disk and thus will no longer exist. 
C) the red giant will probably undergo a supernova explosion within the next million years. 
D) tidal forces from the black hole will rip the planet apart. 
E) the planet's orbit gradually will decay as it is sucked in by the black hole. 
A) jets of material shot out of the accretion disk will shoot down their planet. 
B) their planet receives most of its energy from the red giant.However,this star will soon be completely devoured in the accretion disk and thus will no longer exist. 
C) the red giant will probably undergo a supernova explosion within the next million years. 
D) tidal forces from the black hole will rip the planet apart. 
E) the planet's orbit gradually will decay as it is sucked in by the black hole.

Question 3

Suppose a white dwarf is gaining mass because of accretion in a binary system.What happens if the mass someday reaches the 1.4-solar-mass limit?

Accepted Answer

A) The white dwarf undergoes a catastrophic collapse,leading to a type of supernova that is somewhat different from that which occurs in a massive star but is comparable in energy. 
B) The white dwarf,which is made mostly of carbon,suddenly becomes much hotter in temperature and therefore is able to begin fusing the carbon.This turns the white dwarf back into a star supported against gravity by ordinary pressure. 
C) The white dwarf immediately collapses into a black hole,disappearing from view. 
D) A white dwarf can never gain enough mass to reach the limit because a strong stellar wind prevents the material from reaching it in the first place. 
A) The white dwarf undergoes a catastrophic collapse,leading to a type of supernova that is somewhat different from that which occurs in a massive star but is comparable in energy. 
B) The white dwarf,which is made mostly of carbon,suddenly becomes much hotter in temperature and therefore is able to begin fusing the carbon.This turns the white dwarf back into a star supported against gravity by ordinary pressure. 
C) The white dwarf immediately collapses into a black hole,disappearing from view. 
D) A white dwarf can never gain enough mass to reach the limit because a strong stellar wind prevents the material from reaching it in the first place.

Question 4

Planets have been detected around a pulsar.

Accepted Answer

A) True 
 B)False

Question 5

Most of the gold,platinum,and rare-earth elements present in the universe are created by neutron star mergers.

Accepted Answer

A) True 
 B)False

Question 6

A teaspoonful of white dwarf material on Earth would weigh

Accepted Answer

A) the same as a teaspoonful of Earth-like material. 
B) about the same as Mt.Everest. 
C) about the same as Earth. 
D) a few tons. 
E) a few million tons. 
A) the same as a teaspoonful of Earth-like material. 
B) about the same as Mt.Everest. 
C) about the same as Earth. 
D) a few tons. 
E) a few million tons.

Question 7

From an observational standpoint,what is a pulsar?

Accepted Answer

A) a star that slowly changes its brightness,getting dimmer and then brighter with a period of anywhere from a few hours to a few weeks 
B) an object that emits flashes of light several times per second or more,with near perfect regularity 
C) an object that emits random "pulses" of light that sometimes occur only a fraction of a second apart and other times stop for several days at a time 
D) a star that changes color rapidly,from blue to red and back again 
E) a star that rapidly changes size as it moves off the main sequence 
A) a star that slowly changes its brightness,getting dimmer and then brighter with a period of anywhere from a few hours to a few weeks 
B) an object that emits flashes of light several times per second or more,with near perfect regularity 
C) an object that emits random "pulses" of light that sometimes occur only a fraction of a second apart and other times stop for several days at a time 
D) a star that changes color rapidly,from blue to red and back again 
E) a star that rapidly changes size as it moves off the main sequence

Question 8

How do we know what happens at the event horizon of a black hole?

Accepted Answer

A) Physicists have created miniature black holes in the lab. 
B) Astronomers have sent spacecraft through the event horizon of a nearby black hole. 
C) Astronomers have analyzed the light from matter within the event horizon of many black holes. 
D) Astronomers have detected X-rays from accretion disks around black holes. 
E) We don't know for sure: we only know what to expect based on the predictions of general relativity. 
A) Physicists have created miniature black holes in the lab. 
B) Astronomers have sent spacecraft through the event horizon of a nearby black hole. 
C) Astronomers have analyzed the light from matter within the event horizon of many black holes. 
D) Astronomers have detected X-rays from accretion disks around black holes. 
E) We don't know for sure: we only know what to expect based on the predictions of general relativity.

Question 9

After a massive-star supernova,what is left behind?

Accepted Answer

A) always a white dwarf 
B) always a neutron star 
C) always a black hole 
D) either a white dwarf or a neutron star 
E) either a neutron star or a black hole 
A) always a white dwarf 
B) always a neutron star 
C) always a black hole 
D) either a white dwarf or a neutron star 
E) either a neutron star or a black hole

Question 10

Pulsars are thought to be

Accepted Answer

A) accreting white dwarfs. 
B) rapidly rotating neutron stars. 
C) unstable high-mass stars. 
D) accreting black holes. 
A) accreting white dwarfs. 
B) rapidly rotating neutron stars. 
C) unstable high-mass stars. 
D) accreting black holes.

Question 11

Based on current understanding,the minimum mass of a black hole that forms during a massive star supernova is roughly

Accepted Answer

A) 0.5 solar masses. 
B) 1.4 solar masses. 
C) 3 solar masses. 
D) 10 solar masses. 
A) 0.5 solar masses. 
B) 1.4 solar masses. 
C) 3 solar masses. 
D) 10 solar masses.

Question 12

Imagine that our Sun were magically and suddenly replaced by a black hole of the same mass (1 solar mass).What would happen to Earth in its orbit?

Accepted Answer

A) Earth would almost instantly be sucked into oblivion in the black hole. 
B) Earth would orbit faster,but at the same distance. 
C) Earth would slowly spiral inward until it settled into an orbit about the size of Mercury's current orbit. 
D) Nothing-Earth's orbit would remain the same. 
A) Earth would almost instantly be sucked into oblivion in the black hole. 
B) Earth would orbit faster,but at the same distance. 
C) Earth would slowly spiral inward until it settled into an orbit about the size of Mercury's current orbit. 
D) Nothing-Earth's orbit would remain the same.

Question 13

How are elements more massive than iron produced?

Accepted Answer

A) inside white dwarfs 
B) inside two merging white dwarfs 
C) inside neutron stars 
D) inside two merging neutron stars 
A) inside white dwarfs 
B) inside two merging white dwarfs 
C) inside neutron stars 
D) inside two merging neutron stars

Question 14

No visible light can escape a black hole,but things such as gamma rays,X-rays,and neutrinos can.

Accepted Answer

A) True 
 B)False

Question 15

According to present understanding,a nova is caused by

Accepted Answer

A) hydrogen fusion on the surface of a white dwarf. 
B) carbon fusion in the core of a white dwarf. 
C) hydrogen fusion on the surface of a neutron star. 
D) a white dwarf that gains enough mass to exceed the 1.4-solar-mass limit. 
A) hydrogen fusion on the surface of a white dwarf. 
B) carbon fusion in the core of a white dwarf. 
C) hydrogen fusion on the surface of a neutron star. 
D) a white dwarf that gains enough mass to exceed the 1.4-solar-mass limit.

Question 16

Which of the following is closest in mass to a white dwarf?

Accepted Answer

A) the Moon 
B) Earth 
C) Jupiter 
D) Neptune 
E) the Sun 
A) the Moon 
B) Earth 
C) Jupiter 
D) Neptune 
E) the Sun

Question 17

Should we expect to find abundant amounts of gold and other rare-earth elements elsewhere in the universe?

Accepted Answer

Gold,platinum,and other rare-earth eleme

Exam 18: The Bizarre Stellar Graveyard

Which of the following is closest in size (radius)to a neutron star?

Suppose a white dwarf is gaining mass because of accretion in a binary system.What happens if the mass someday reaches the 1.4-solar-mass limit?

Planets have been detected around a pulsar.

Most of the gold,platinum,and rare-earth elements present in the universe are created by neutron star mergers.

A teaspoonful of white dwarf material on Earth would weigh

From an observational standpoint,what is a pulsar?

How do we know what happens at the event horizon of a black hole?

After a massive-star supernova,what is left behind?

Pulsars are thought to be

Based on current understanding,the minimum mass of a black hole that forms during a massive star supernova is roughly

Imagine that our Sun were magically and suddenly replaced by a black hole of the same mass (1 solar mass).What would happen to Earth in its orbit?

How are elements more massive than iron produced?

No visible light can escape a black hole,but things such as gamma rays,X-rays,and neutrinos can.

According to present understanding,a nova is caused by

Which of the following is closest in mass to a white dwarf?

Should we expect to find abundant amounts of gold and other rare-earth elements elsewhere in the universe?

A Modern View of the Universe

Discovering the Universe for Yourself

The Science of Astronomy

Making Sense of the Universe: Understanding Motion, Energy, and Gravity

Light and Matter: Reading Messages from the Cosmos

Telescopes: Portals of Discovery

Our Planetary System

Formation of the Solar System

Planetary Geology: Earth and the Other Terrestrial Worlds

Planetary Atmospheres: Earth and the Other Terrestrial Worlds

Jovian Planet Systems

Asteroids, Comets, and Dwarf Planets: Their Nature, Orbits, and Impacts

Other Planetary Systems: The New Science of Distant Worlds

Our Star

Surveying the Stars

Star Birth

Star Stuff

Our Galaxy

Galaxies and the Foundations of Modern Cosmology

Galaxy Evolution

The Birth of the Universe

Dark Matter, Dark Energy, and the Fate of the Universe

Life in the Universe

Celestial Timekeeping and Navigation

Space and Time

Spacetime and Gravity

Building Blocks of the Universe

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