Question 1

A black hole is so named because:

Accepted Answer

A)   no light or other electromagnetic radiation can escape from inside it.
B)   its electromagnetic radiation is gravitationally redshifted to the infrared, leaving no light in the optical region.
C)   it emits a perfect blackbody spectrum.
D)   it is colder than the rest of the universe; that is, its effective temperature is less than 3 K.E) A) and C)
F) B) and C)

Question 2

The diameter of a typical planetary nebula,after 10,000 years of expansion,is:

Accepted Answer

A)   about 1000 ly.
B)   about 1 AU.
C)   only about 3 to 5 stellar diameters.
D)   a few light-years.E) A) and C)
F) B) and C)

Question 3

Planetary nebulae are so named because:

Accepted Answer

A)   they were extended objects, often green-colored, that looked like planets when first seen by nineteenth-century observers through their telescopes.
B)   the ejected material is rich in carbon and oxygen, necessary elements for the manufacture of planets in the nebulae surrounding stars.
C)   they rotate slowly and condense into planetary objects around a central star.
D)   their spectra appear to be similar to the spectra of the giant gas planets in the solar system.E) A) and D)
F) None of the above

Question 4

Sometimes particle-antiparticle pairs are created and then annihilate so quickly that we cannot know that they ever existed.What are these particles (or antiparticles) called?

Accepted Answer

A)   relativistic particles
B)   temporary particles
C)   field particles
D)   virtual particlesE) A) and D)
F) B) and C)

Question 5

How many neutrinos from supernova SN 1987A were detected on Earth?

Accepted Answer

A)   none
B)   about 400,000
C)   8 × 10¹⁷
D)   20E) B) and D)
F) All of the above

Question 6

A planetary nebula is a:

Accepted Answer

A)   gas shell, the atmosphere of a red giant star, slowly expanding away from the core of the star.
B)   contracting spherical cloud of gas surrounding a newly formed star in which planets are forming.
C)   nebula caused by the supernova explosion of a massive star.
D)   disk-shaped nebula of dust and gas rotating around a relatively young star in which planets will eventually form.E) A) and D)
F) All of the above

Question 7

What is a virtual particle?

Accepted Answer

A)   a particle whose existence is too short for us to know it ever existed
B)   a particle that never does anything wrong
C)   a particle that, if it comes in contact with ordinary matter, annihilates to form pure energy
D)   a particle, like a photon or a graviton, that is made up of wavesE) C) and D)
F) B) and D)

Question 8

Matter in an accretion disk is in orbit around a black hole,but friction within the disk causes the matter to gradually spiral into the black hole.What will change in terms of the observable properties of the black hole as this process continues?

Accepted Answer

A)   Only the mass will increase.
B)   The mass, the angular momentum, and the rate of evaporation of the black hole will increase.
C)   Nothing will change.
D)   Both the mass and the angular momentum of the black hole will increase.E) A) and D)
F) A) and C)

Question 9

Which sentence about supernova SN 1987A is NOT true?

Accepted Answer

A)   Bursts of neutrinos were detected at several sites from the supernova.
B)   The supernova did not become as intrinsically bright as originally expected.
C)   The supernova was a white dwarf exploding after mass transfer from a companion star in a binary star system.
D)   Observations of the star had been made before it blew up.E) A) and B)
F) B) and C)

Question 10

The nova phenomenon,an occasional and sometimes repeated intense brightening of a star by a factor of about 10⁶,is caused by:

Accepted Answer

A)   a beam of radiation from a nearby pulsar illuminating the surface of a red giant star and inducing rapid and intense heating.
B)   the capture and rapid compression of matter by a black hole.
C)   the explosion of a single massive star at the end of its thermonuclear fusion phases.
D)   explosive hydrogen fusion on the surface of a white dwarf star after mass transfer from a companion star in a binary system.E) All of the above
F) A) and B)

Question 11

We have considered red dwarf stars that convert all their hydrogen to helium and then stop evolving.What is the maximum mass limit of a red dwarf star?

Accepted Answer

A)   0.4 M
B)   0.8 M
C)   2 M
D)   8 ME) None of the above
F) All of the above

Question 12

Which object is NOT an end point of a star's evolutionary life?

Accepted Answer

A)   a red giant
B)   a supernova
C)   a black hole
D)   a neutron starE) C) and D)
F) A) and C)

Question 13

What name is given to a nonrotating black hole?

Accepted Answer

A)   wormhole
B)   Hawking singularity
C)   Schwarzschild black hole
D)   Kerr black holeE) All of the above
F) None of the above

Question 14

Which statement does NOT describe a consequence of core collapse at the end of the life of a massive star?

Accepted Answer

A)   The silicon core is converted to iron by fusion reactions.
B)   Electrons combine with protons to form neutrons.
C)   Great numbers of neutrinos are produced.
D)   The core density approaches the density of an atomic nucleus.E) B) and C)
F) A) and D)

Question 15

The Schwarzschild radius is:

Accepted Answer

A)   half the diameter of the singularity in a black hole.
B)   the distance to which gas is ejected in a planetary nebula.
C)   half the diameter of a neutron star.
D)   the distance from the center of a black hole to the point at which the escape velocity becomes equal to the speed of light.E) A) and D)
F) B) and C)

Question 16

The MOST recent supernova explosion known to have occurred in the Milky Way Galaxy:

Accepted Answer

A)   was seen in 1987 (supernova 1987
A)  .
B)   created the Gum Nebula.
C)   gave rise to the Crab Nebula.
D)   created the supernova remnant Cassiopeia A.E) A) and B)
F) All of the above

Question 17

Which important component does a planetary nebula contribute to the interstellar medium?

Accepted Answer

A)   molecules such as NH₃ and CH₄, which contribute to giant molecular clouds
B)   UV light that photoionizes hydrogen. The hydrogen, on recombination, produces the red Balmer α light by which we see interstellar emission nebulae.
C)   rotational motion from the original star, which serves to concentrate interstellar matter into new stars and planetary systems
D)   nuclei of moderately heavy elements, major components of planets such as our ownE) A) and D)
F) B) and C)

Question 18

Which type of dwarf is largest?

Accepted Answer

A)   white
B)   red
C)   brown
D)   All are about the same size.E) A) and D)
F) A) and B)

Question 19

The source of the beams of electromagnetic radiation (including light in some cases) emitted by pulsars is:

Accepted Answer

A)   charged particles traveling along the magnetic axes of rotating neutron stars; the particles emit light as they are accelerated.
B)   electrons flowing out along the rotation axis of an accretion disk around a neutron star; the electrons are accelerated and hence emit light.
C)   the surface of a normal star that has a white dwarf companion; the white dwarf creates a hot spot on the normal star that emits a beam of light as the stars rotate around each other.
D)   jets of material flowing out along the rotation axis of the accretion disk around a black hole; collisions in the jets heat the material and produce light.E) A) and B)
F) None of the above

Question 20

A compact body pulls material from a binary companion.This material plunges toward the compact body,forms an accretion disk,and emits X-rays.Which phenomenon would this description NOT fit?

Accepted Answer

A)   a pulsating X-ray source
B)   an X-ray burster
C)   a black hole in a binary system
D)   a novaE) B) and C)
F) A) and B)

Exam 12: The Deaths and Remnants of Stars

What is a virtual particle?

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Planetary nebulae are so named because:

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Which object is NOT an end point of a star's evolutionary life?

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The source of the beams of electromagnetic radiation (including light in some cases) emitted by pulsars is:

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A black hole is so named because:

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How many neutrinos from supernova SN 1987A were detected on Earth?

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Which type of dwarf is largest?

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Which statement does NOT describe a consequence of core collapse at the end of the life of a massive star?

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The nova phenomenon,an occasional and sometimes repeated intense brightening of a star by a factor of about 10⁶,is caused by:

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A planetary nebula is a:

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Sometimes particle-antiparticle pairs are created and then annihilate so quickly that we cannot know that they ever existed.What are these particles (or antiparticles) called?

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The diameter of a typical planetary nebula,after 10,000 years of expansion,is:

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A compact body pulls material from a binary companion.This material plunges toward the compact body,forms an accretion disk,and emits X-rays.Which phenomenon would this description NOT fit?

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The MOST recent supernova explosion known to have occurred in the Milky Way Galaxy:

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The Schwarzschild radius is:

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Which sentence about supernova SN 1987A is NOT true?

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Which important component does a planetary nebula contribute to the interstellar medium?

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What name is given to a nonrotating black hole?

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We have considered red dwarf stars that convert all their hydrogen to helium and then stop evolving.What is the maximum mass limit of a red dwarf star?

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Matter in an accretion disk is in orbit around a black hole,but friction within the disk causes the matter to gradually spiral into the black hole.What will change in terms of the observable properties of the black hole as this process continues?

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