Why Is the Sun Very Dense on the Inside? Why Is the Sun Very Dense on the Inside?

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Why does the Sun shine? Why does the Sun shine? Why is the Sun very dense on the inside? Why is the Sun very dense on the inside?

a) It is on fire. a) It is on fire. a) Denser materials sank to its center. a) Denser materials sank to its center. b) chemical energy b) chemical energy b) Pressure of the overlying gas keeps the density b) Pressure of the overlying gas keeps the density c) gravitational energy c) gravitational energy high. high. d) nuclear fusion d) nuclear fusion c) It formed from dense material. c) It formed from dense material. e) nuclear fission e) nuclear fission d) Nuclear fusion increases the density in the core by d) Nuclear fusion increases the density in the core by changing hydrogen into helium. changing hydrogen into helium.

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What conditions are required for nuclear fusion What conditions are required for nuclear fusion What is a hydrogen nucleus–the particle that What is a hydrogen nucleus–the particle that of hydrogen to occur? of hydrogen to occur? fuses into helium in the Sun? fuses into helium in the Sun?

a) a temperature of millions Kelvin a) a temperature of millions Kelvin a) a neutron a) a neutron b) high density b) high density b) a proton b) a proton c) the presence of uranium c) the presence of uranium c) an electron c) an electron d) all of the above d) all of the above d) a positron d) a positron e) A and B e) A and B

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What kind of radiation do you think shines out What kind of radiation do you think shines out If the Sun's core went out of balance and If the Sun's core went out of balance and of the core of the Sun? of the core of the Sun? shrank a little, what would happen? shrank a little, what would happen?

a) visible light a) visible light a) The density would decrease, and fusion would slow a) The density would decrease, and fusion would slow b) infrared light b) infrared light down, releasing less energy. down, releasing less energy. c) X-ray light c) X-ray light b) The density would increase, and fusion would b) The density would increase, and fusion would speed up, releasing more energy. speed up, releasing more energy. d) ultraviolet light d) ultraviolet light e) gamma rays e) gamma rays c) The whole Sun would shrink. c) The whole Sun would shrink. d) Not much would change. d) Not much would change.

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If the fusion in the Sun's core sped up slightly, If the fusion in the Sun's core sped up slightly, How do photons get from the core of the Sun to How do photons get from the core of the Sun to releasing more energy, what would happen? releasing more energy, what would happen? the surface? the surface?

a) The entire Sun would become hotter. a) The entire Sun would become hotter. a) They bounce from atom to atom, being absorbed a) They bounce from atom to atom, being absorbed b) The core would expand. b) The core would expand. and reemitted as they make their way to the and reemitted as they make their way to the c) The color of the Sun would change. c) The color of the Sun would change. surface. surface. b) They are brought to the surface by conduction. b) They are brought to the surface by conduction. d) all of the above d) all of the above c) They are brought to the surface by convection. c) They are brought to the surface by convection. d) none of the above d) none of the above

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By the time photons reach the surface of the By the time photons reach the surface of the If we can't see the Sun's interior, how do we If we can't see the Sun's interior, how do we Sun, they are mostly Sun, they are mostly know what it is like? know what it is like?

a) infrared light. a) infrared light. a) observations of sunquakes a) observations of sunquakes b) visible light. b) visible light. b) observations of neutrinos b) observations of neutrinos c) ultraviolet light. c) ultraviolet light. c) our understanding of gravitational equilibrium c) our understanding of gravitational equilibrium d) X rays. d) X rays. d) all of the above d) all of the above e) gamma rays. e) gamma rays. e) B and C e) B and C

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The Sun's visible surface, or photosphere, has The Sun's visible surface, or photosphere, has Since the Sun's outer atmosphere, or corona, is Since the Sun's outer atmosphere, or corona, is regions of strong magnetic field called regions of strong magnetic field called millions of degrees but not very dense, millions of degrees but not very dense,

a) granulation. a) granulation. a) we can't really see it in any wavelength. a) we can't really see it in any wavelength. b) magnetic traps. b) magnetic traps. b) we see it very clearly in visible light. b) we see it very clearly in visible light. c) magnetic lines. c) magnetic lines. c) we see X rays coming from it. c) we see X rays coming from it. d) sunspots. d) sunspots. d) we only see the lower layers of the Sun's d) we only see the lower layers of the Sun's e) sundogs. e) sundogs. atmosphere, which are much more dense. atmosphere, which are much more dense.

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What is the solar activity cycle? What is the solar activity cycle? How does solar activity affect Earth? How does solar activity affect Earth?

a) the balance of pressure and gravity in the Sun's a) the balance of pressure and gravity in the Sun's a) It can make beautiful aurora. a) It can make beautiful aurora. core core b) It can cause geomagnetic storms. b) It can cause geomagnetic storms. b) the process of fusing hydrogen into helium b) the process of fusing hydrogen into helium c) It can damage satellites. c) It can damage satellites. c) the 11-year cycle of changes in the occurrence of c) the 11-year cycle of changes in the occurrence d) It can disrupt electrical power. d) It can disrupt electrical power. sunspots, flares, and solar wind of sunspots, flares, and solar wind e) all of the above e) all of the above d) the process by which photons from the Sun's core d) the process by which photons from the Sun's core make their way to the surface make their way to the surface

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If fusion in the solar core ceased today, If fusion in the solar core ceased today, Which of the following can be used to directly Which of the following can be used to directly worldwide panic would break out tomorrow worldwide panic would break out tomorrow measure the Sun's mass? measure the Sun's mass? as the Sun began to grow dimmer. as the Sun began to grow dimmer.

a) solar luminosity and Earth-Sun distance a) solar luminosity and Earth-Sun distance a) Yes, because Earth would quickly freeze over. a) Yes, because Earth would quickly freeze over. b) solar temperature and Earth-Sun distance b) solar temperature and Earth-Sun distance b) Yes, because Earth would no longer be bound to the b) Yes, because Earth would no longer be bound to the solar system and would drift into space. solar system and would drift into space. c) solar rotation rate and Earth-Sun distance. c) solar rotation rate and Earth-Sun distance. c) Yes, because the Sun would collapse and the planets c) Yes, because the Sun would collapse and the planets d) Earth's mass and orbital period d) Earth's mass and orbital period would soon follow. would soon follow. e) The Venus-Sun distance and the length of a e) The Venus-Sun distance and the length of a d) No, it takes thousands of years for photons created in d) No, it takes thousands of years for photons created in Venusian year Venusian year nuclear reactions at the solar core to reach the surface. nuclear reactions at the solar core to reach the surface. e) No, the Sun would continue to glow brightly for billions of e) No, the Sun would continue to glow brightly for billions of years because of gravitational contraction. years because of gravitational contraction. © 2014 Pearson Education, Inc. © 2014 Pearson Education, Inc. © 2014 Pearson Education, Inc. © 2014 Pearson Education, Inc. Chapter 14-16 Review Chapter 14-16 Review Chapter 14-16 Review Chapter 14-16 Review

If you want to see a lot of sunspots, just wait for If you want to see a lot of sunspots, just wait for If a star was moved twice as far away, what If a star was moved twice as far away, what the time of solar maximum. the time of solar maximum. would happen to it? would happen to it?

a) Yes, the number of sunspots peaks at solar a) Yes, the number of sunspots peaks at solar a) It would get twice as faint. a) It would get twice as faint. maximum. maximum. b) It would get four times as faint. b) It would get four times as faint. b) No, the number of sunspots peaks at solar b) No, the number of sunspots peaks at solar c) It would get eight times as faint. c) It would get eight times as faint. minimum. minimum. d) It would get fainter and redder. d) It would get fainter and redder. c) No, the number of sunspots is random and does c) No, the number of sunspots is random and does e) It would get fainter and bluer. e) It would get fainter and bluer. not depend on whether it is the time of solar not depend on whether it is the time of solar minimum or maximum. minimum or maximum.

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How do we determine the distances to nearby How do we determine the distances to nearby How can you tell the temperatures of stars? How can you tell the temperatures of stars? stars? stars?

a) radar a) radar a) color–the hottest stars are "red hot" a) color–the hottest stars are "red hot" b) parallax b) parallax b) color–the hottest stars are "bluish white" b) color–the hottest stars are "bluish white" c) measuring luminosity, radius, and temperature, and c) measuring luminosity, radius, and temperature, and c) spectral type c) spectral type inferring the distance inferring the distance d) A and C d) A and C d) comparing observed brightness to the Sun, and d) comparing observed brightness to the Sun, and e) B and C e) B and C inferring the distance inferring the distance

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In binary stars, the orbital period depends on In binary stars, the orbital period depends on Why do the hottest spectra (types O and B) Why do the hottest spectra (types O and B) the masses of the stars and the sizes of their the masses of the stars and the sizes of their show few absorption lines? show few absorption lines? orbits. Why is this so valuable to know? orbits. Why is this so valuable to know?

a) Many elements have been used up in these stars. a) Many elements have been used up in these stars. a) We can predict how long an orbit will take. a) We can predict how long an orbit will take. b) These stars are old and were formed before there b) These stars are old and were formed before there b) This is the main way we determine the masses b) This is the main way we determine the masses were heavy elements in the galaxy. were heavy elements in the galaxy. of stars. of stars. c) Many atoms in these stars are ionized–have lost c) Many atoms in these stars are ionized–have lost c) This lets us know if two stars that look close c) This lets us know if two stars that look close electrons–and can't absorb photons. electrons–and can't absorb photons. together in the sky really orbit one another. together in the sky really orbit one another.

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What is the X-axis in an H-R diagram? What is the X-axis in an H-R diagram? What is the Y-axis in an H-R diagram? What is the Y-axis in an H-R diagram?

a) color a) color a) Color a) Color b) temperature b) temperature b) Temperature b) Temperature c) spectral type c) spectral type c) Spectral type c) Spectral type d) all of the above d) all of the above d) Luminosity d) Luminosity

In a random sample of stars in the Sun's In a random sample of stars in the Sun's Stars spend about 90% of their life Stars spend about 90% of their life neighborhood, you would expect about 90% neighborhood, you would expect about 90% of them to be of them to be

a) as protostars. a) as protostars. a) red giants. a) red giants. b) as main-sequence stars. b) as main-sequence stars. b) white dwarfs. b) white dwarfs. c) as red giants. c) as red giants. c) main sequence stars. c) main sequence stars. d) as planetary nebulae. d) as planetary nebulae. d) protostars. d) protostars.

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To measure a star's luminosity, you need to To measure a star's luminosity, you need to What is the fundamental way of measuring the What is the fundamental way of measuring the know know distance to the stars? distance to the stars?

a) its temperature and distance. a) its temperature and distance. a) radar a) radar b) its temperature and color. b) its temperature and color. b) the H-R diagram b) the H-R diagram c) its apparent brightness and distance. c) its apparent brightness and distance. c) measuring apparent brightness c) measuring apparent brightness d) its apparent brightness and color. d) its apparent brightness and color. d) parallax d) parallax e) its distance, apparent brightness, and color. e) its distance, apparent brightness, and color. e) Doppler shifts e) Doppler shifts

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Which of the following in an example of Which of the following in an example of A star near the top of the main sequence has A star near the top of the main sequence has parallax? parallax? a mass about a mass about

a) Hold your thumb out and blink one eye at a time. Your thumb a) Hold your thumb out and blink one eye at a time. Your thumb a) twice the Sun's mass. a) twice the Sun's mass. moves more than the background. moves more than the background. b) five times the Sun's mass. b) five times the Sun's mass. b) Driving down a road, a nearby fence appears to shift more b) Driving down a road, a nearby fence appears to shift more than distance scenery. than distance scenery. c) 60 times the Sun's mass. c) 60 times the Sun's mass. c) Planets shift their position in the sky partly because Earth c) Planets shift their position in the sky partly because Earth d) 10,000 times the Sun's mass. d) 10,000 times the Sun's mass. moves, shifting our position. moves, shifting our position. d) Stars shift their position at different times of the year as d) Stars shift their position at different times of the year as Earth orbits the Sun. Earth orbits the Sun. e) all of the above e) all of the above © 2014 Pearson Education, Inc. © 2014 Pearson Education, Inc. © 2014 Pearson Education, Inc. © 2014 Pearson Education, Inc.

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How would you expect the lifetime of a massive How would you expect the lifetime of a massive A star near the top of the main sequence has A star near the top of the main sequence has star near the top of the main sequence to star near the top of the main sequence to a luminosity about a luminosity about compare to the Sun's? compare to the Sun's?

a) twice the Sun's luminosity. a) twice the Sun's luminosity. a) It would be longer. a) It would be longer. b) five times the Sun's luminosity. b) five times the Sun's luminosity. b) It would be about the same. b) It would be about the same. c) 20 to 30 times the Sun's luminosity. c) 20 to 30 times the Sun's luminosity. c) It would be shorter. c) It would be shorter. d) 10,000 times the Sun's luminosity. d) 10,000 times the Sun's luminosity. d) It would be much shorter. d) It would be much shorter.

Clusters in the disk of our galaxy, with hundreds Clusters in the disk of our galaxy, with hundreds Clusters in the halo of our galaxy, with hundreds Clusters in the halo of our galaxy, with hundreds of stars in them, are called of stars in them, are called of thousands of stars in them, are called of thousands of stars in them, are called

a) open clusters. a) open clusters. a) open clusters. a) open clusters. b) globular clusters. b) globular clusters. b) globular clusters. b) globular clusters.

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Why do photographs of a star field show some Why do photographs of a star field show some What do the colors of stars in the Hertzsprung- What do the colors of stars in the Hertzsprung- stars to be larger than others? stars to be larger than others? Russell diagram tell us? Russell diagram tell us?

a) Some stars are larger than others and therefore appear larger. a) Some stars are larger than others and therefore appear larger. a) the size of the star a) the size of the star b) Some stars are nearer than others and therefore appear larger. b) Some stars are nearer than others and therefore appear larger. b) the luminosity of the star b) the luminosity of the star c) Photographs make brighter stars appear larger than fainter c) Photographs make brighter stars appear larger than fainter stars, although they should all be points of light. stars, although they should all be points of light. c) the surface temperature of the star c) the surface temperature of the star d) Sometimes what looks like a single star is actually a small d) Sometimes what looks like a single star is actually a small d) the core temperature of the star d) the core temperature of the star group of stars and therefore appears larger. group of stars and therefore appears larger. e) the mass of the star e) the mass of the star

Chapter 14-16 Review Chapter 14-16 Review Chapter 14-16 Review Chapter 14-16 Review True or False?: Stars that begin their lives with True or False?: Stars that begin their lives with True or False?: Two stars that look very different True or False?: Two stars that look very different the most mass live longer than less massive the most mass live longer than less massive must be made of different kinds of elements. must be made of different kinds of elements. stars because it takes them a lot longer to use stars because it takes them a lot longer to use up their hydrogen fuel. up their hydrogen fuel.

a) True, stars have a wide range of compositions. a) True, stars have a wide range of compositions. a) True, with more hydrogen to burn, massive stars can live for a) True, with more hydrogen to burn, massive stars can live for billions of years. billions of years. b) True, stars appear different because of their different b) True, stars appear different because of their different b) True, low mass stars run out of hydrogen very quickly and b) True, low mass stars run out of hydrogen very quickly and composition. composition. have very short lifetimes. have very short lifetimes. c) False, stars appear different due to their different c) False, stars appear different due to their different c) False, stars have similar lifetimes despite their different c) False, stars have similar lifetimes despite their different ages and masses, not composition. ages and masses, not composition. masses. masses. d) False, stars appear different because of their varying d) False, stars appear different because of their varying d) False, more massive stars are much more luminous than low d) False, more massive stars are much more luminous than distances from us. distances from us. mass stars and use up their hydrogen faster, even though low mass stars and use up their hydrogen faster, even they have more of it. though they have more of it.

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True or False?: A protostellar cloud spins faster True or False?: A protostellar cloud spins faster What is the first step in the formation of a What is the first step in the formation of a as it contracts, even though its angular as it contracts, even though its angular protostar? protostar? momentum stays the same. momentum stays the same.

a) Conservation of angular momentum causes galactic a) Conservation of angular momentum causes galactic a) True, angular momentum is conserved and if the a) True, angular momentum is conserved and if the material to collapse into a disk. material to collapse into a disk. cloud contracts, it must spin faster. cloud contracts, it must spin faster. b) Gravity causes planetesimals to begin to accumulate. b) Gravity causes planetesimals to begin to accumulate. b) True, clouds spin faster as they contract but their b) True, clouds spin faster as they contract but their angular momentum must also increase. angular momentum must also increase. c) Gravity causes a cloud of gas and dust to begin to c) Gravity causes a cloud of gas and dust to begin to contract. contract. c) False, if the angular momentum stays the same, the c) False, if the angular momentum stays the same, the cloud must spin at the same rate. cloud must spin at the same rate. d) Nuclear fusion heats material and causes it to glow. d) Nuclear fusion heats material and causes it to glow. d) False, if the angular momentum stays the same, the d) False, if the angular momentum stays the same, the cloud cannot contract. cloud cannot contract.

Why do we think that clouds of gas and dust Why do we think that clouds of gas and dust If gas and dust are dark, how do we know they If gas and dust are dark, how do we know they form stars? form stars? exist in space? exist in space?

a) We see young star clusters with gas and dust around them. a) We see young star clusters with gas and dust around them. a) We sometimes see absorption lines from a) We sometimes see absorption lines from b) Infrared and microwave telescopes let us see protostars inside b) Infrared and microwave telescopes let us see protostars inside interstellar gas. interstellar gas. dust clouds. dust clouds. b) Infrared telescopes can see cool dust. b) Infrared telescopes can see cool dust. c) Computer models predict that if a cloud has enough mass, it c) Computer models predict that if a cloud has enough mass, it will contract, heat up, and form a star. will contract, heat up, and form a star. c) Radio telescopes can detect interstellar gas. c) Radio telescopes can detect interstellar gas. d) The Hubble Telescope lets us watch stars form before our d) The Hubble Telescope lets us watch stars form before our d) All of the above. d) All of the above. eyes. eyes. e) All but D e) All but D

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What is the energy source that heats a What is the energy source that heats a When starlight passes through interstellar dust, When starlight passes through interstellar dust, contracting protostar? contracting protostar?

a) it gets fainter. a) it gets fainter. a) friction a) friction b) the blue light tends to scatter while the red continues b) the blue light tends to scatter while the red continues b) pressure b) pressure toward us. toward us. c) gravitational potential energy c) gravitational potential energy c) wavelengths all get longer (redder). c) wavelengths all get longer (redder). d) fusion d) fusion d) all of the above d) all of the above e) kinetic energy e) kinetic energy e) A and B e) A and B

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Why do protostars rotate rather fast and end up Why do protostars rotate rather fast and end up Why can't a cloud with less than 0.08 solar Why can't a cloud with less than 0.08 solar surrounded by disks of material? surrounded by disks of material? masses become a star? masses become a star?

a) The galaxy is rotating, so all the stars that form are a) The galaxy is rotating, so all the stars that form are a) There won't be enough time for a star to form before a) There won't be enough time for a star to form before rotating as well. rotating as well. gas is blown away by neighboring stars. gas is blown away by neighboring stars. b) If a cloud spins even a little bit, the spin increases b) If a cloud spins even a little bit, the spin increases b) Gravity will be too weak to make the cloud collapse b) Gravity will be too weak to make the cloud collapse as it contracts. as it contracts. into a star. into a star. c) conservation of angular momentum c) conservation of angular momentum c) It will never get hot enough for fusion to start. c) It will never get hot enough for fusion to start. d) all of the above d) all of the above d) The cloud will form planets instead of a star. d) The cloud will form planets instead of a star. e) B and C e) B and C

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Why can't a cloud with more than about 150 Why can't a cloud with more than about 150 If a protostar doesn't have enough mass to If a protostar doesn't have enough mass to solar masses become a star? solar masses become a star? become a star, it becomes a become a star, it becomes a

a) There's rarely enough material to make a star so a) There's rarely enough material to make a star so a) dark dwarf. a) dark dwarf. massive. massive. b) brown dwarf. b) brown dwarf. b) A larger star would be so bright that radiation b) A larger star would be so bright that radiation c) white dwarf. c) white dwarf. pressure would blow it apart. pressure would blow it apart. c) Gravity would be so strong that it would become a c) Gravity would be so strong that it would become a d) black dwarf. d) black dwarf. black hole. black hole. d) The star's energy would be so great that it would d) The star's energy would be so great that it would explode as a supernova. explode as a supernova.

Compared to stars like the Sun, how common Compared to stars like the Sun, how common What stops the contraction of a protostar? What stops the contraction of a protostar? are massive (10, 20, 30 solar mass) stars? are massive (10, 20, 30 solar mass) stars?

a) degeneracy pressure a) degeneracy pressure a) much more common a) much more common b) density b) density b) more common b) more common c) nuclear reactions c) nuclear reactions c) less common c) less common d) solidification of the core d) solidification of the core d) much less common d) much less common e) none of the above e) none of the above e) equally common e) equally common