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Chapter 14The Stars:

How much longer can the Sun sustain life on Earth?

1. The energy source of stars is primarily associated witha. the reactions of atoms in the star corona.b. the reactions of nuclei in the star core.c. the reactions of atoms in the outer regions of the star.d. burning of elements until they become radioactive.e. burning of elements heavier than lead.

Ans: bLink To: The Anatomy of StarsDifficulty Level: Easy

2. If scientists located a Dyson Sphere, they would finda. something made from a dismantled planet.b. a planet in orbit around our closest star.c. an energy source built to surround a planet.d. an object at the core of the Sun.e. the corona during a total eclipse.

Ans: aLink To: The Anatomy of StarsDifficulty Level: Easy

3. The solar winda. extends into space as far as Mercury.b. consists of hydrogen and carbon particles.c. is a part of the Sun’s atmospheric circulation.d. affects the magnetic fields of planets.e. is another term for the Sun’s chromosphere.

Ans: dLink To: The Anatomy of StarsDifficulty Level: Easy4. Which of the following can be said about large stars?

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a. Large stars have a longer lifetime than smaller stars.b. Large stars have a shorter lifetime than smaller stars.c. Large star lifetime is about the same as that of smaller stars.d. The helium in the large star's core burns to produce hydrogen.e. Large stars are the source of oxygen in photosynthesis.

Ans: bLink To: The Life Cycles of StarsDifficulty Level: Easy

5. At this moment, the Sun is producing energy by burninga. plutonium.b. anthracite.c. hydrogen.d. helium.e.iron.

Ans: cLink To: The Anatomy of StarsDifficulty Level: Easy

6. The end products of fusion in the Sun's core area. helium isotopes, protons, and gamma rays.b. hydrogen isotopes, photons, and infrared rays.c. helium ions, photons, and hydrogen isotopes.d. hydrogen ions, protons, and gamma rays.e. deuterium, photons, and gamma rays.

Ans: aLink To: The Anatomy of StarsDifficulty Level: Easy

7. Approximately how long does it take the energy of the Sun to be transferred from the stellar core to the photosphere?a. one light-yearb. many thousands of years c. 24 hoursd. one monthe. eight minutes

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Ans: bLink To: The Anatomy of StarsDifficulty Level: Easy

8. Which of the following affect the life of a star?a. gravitational forceb. massc. temperatured. fusion processese. all of the above

Ans: eLink To: The Life Cycles of StarsDifficulty Level: Easy

9. From what part of the electromagnetic spectrum is most of the Sun’s energy emitted?a. radio wavesb .infrared wavesc. visible light wavesd. gamma rayse. microwaves

Ans: cLink To: The Nature of StarsDifficulty Level: Easy

10. Which of the following satellite observatories could not detect the presence of a black hole?a. Compton Gamma Ray Observatory (GRO)b. Chandra X-ray Observatoryc. Hubble Space Telescope (HST)d. Space Infrared Telescope Facility (SIRTF)e. only a and b

Ans: dLink To: The Nature of StarsDifficulty Level: Medium

11. Differences in how a star appears in the sky are a function ofa. the size of the star.

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b. how far away the star is from Earth.c. the total energy emitted by the star.d. the star’s apparent brightness.e. all of the above

Ans: eLink To: The Variety of StarsDifficulty Level: Easy

12. The Hertzsprung-Russell diagram is a graphical technique used in astronomy to comparea. the surface temperature versus the energy output of a star.b. the star’s luminosity versus its distance from Earth.c. the absolute magnitude of the star versus the star’s relative temperature.d. the distance the Sun is from the nearest red giant.e. the location of possible solar systems in the Milky Way.

Ans: aLink To: The Life Cycles of StarsDifficulty Level: Easy

13. Where in the Milky Way galaxy would astronomers expect to find planetary systems other than our own?a. Dyson Sphereb. nebulaec. supernovasd. black holee. Cepheid stars


14. Which of the following is not an endpoint of stellar evolution?a. white dwarfb. main sequence starc. pulsard. black holee. neutron star

Ans: b

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Link To: The Life Cycles of StarsDifficulty Level: Easy

15. Where were the heaviest chemical elements on Earth created?a. neutron starsb. black holesc. the Sund. supernovaee. the asteroid belt

Ans: dLink To: The Life Cycles of StarsDifficulty Level: Easy

16. If you were to observe a pulsar, what would you see?a. a blinking red glowb. intermittent radio wavesc. a steady glow that oscillates among the starsd. the sudden brightening of a stare. the total eclipse of the Sun


17. What is Supernova 1987A likely to become?a. black holeb. pulsarsc. main sequence stard. Cepheid variablee. solar wind


18. If the Hubble telescope detects an intensely bright region in the sky that lasts only a few days, it has probably found evidence of aa. white dwarf.

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b. supernova.c. main sequence star.d. new galaxy.e. black hole.

Ans: bLink To: The Nature of StarsDifficulty Level: Easy

19. Which of the following star variables would not be in an astronomer’s data?a. wave lengthb. intensityc. soundd. positione. brightness

Ans: cLink To: The Nature of StarsDifficulty Level: Easy

20. Which of the following telescopes would have a collecting mirror?a. Chandra X-ray orbiting observatory telescope b. Hubble telescopec. Very Large Array telescope in New Mexicod. Hertzsprung-Russell telescope at Harvarde. all of the above

Ans: bLink To: The Nature of StarsDifficulty Level: Easy

21. Which of the following is among the things scientists predict for Sun's demise?a. The burning of helium will produce a carbon ash core.b. The Sun will expand until it extends past the present orbit of Venus.c. The sun will emit more energy but appear to be cool.d. At different points in its final years, the Sun will become a red giant and a white dwarf.e. All of the above are true.

Ans: eLink To: The Life Cycles of Stars

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Difficulty Level: Easy

22. Red giants can be described asa. huge planets that are surrounded by gases.b. large stars that emit a lot of energy but have cool surfaces.c. large stars that emit a lot of energy but have glowing, hot surfaces.d. stars that are in the hydrogen-burning stage of their lives.e. large planets with glowing iron oxide surfaces.


23. The starry night sky seen from Earth is a temporary phenomenon that has lasted about 15 billion years.

Ans: TrueLink To: The Nature of StarsDifficulty Level: Easy

24. Some stars will burn forever.

Ans: FalseLink To: The Life Cycles of StarsDifficulty Level: Easy

25. The Sun's peak output of energy is within the visible spectrum.

Ans: TrueLink To: The Anatomy of StarsDifficulty Level: Easy

26. Record numbers of neutrinos from the Sun have been isolated at the solar neutrino laboratory in South Dakota.

Ans: False

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Link To: The Anatomy of StarsDifficulty Level: Easy

27. All objects with temperatures above absolute zero will radiate some form of electromagnetic waves.


28. Except for visible light and radio waves, the atmosphere of the Earth is opaque to most of the electromagnetic spectrum.


29. The absolute magnitude of a star is the brightness as seen from Earth, depending on the star’s distance from Earth.

Ans: FalseLink To: The Variety of StarsDifficulty Level: Easy

30. The distance to stars greater than 500 light-years away is measured using Cepheid variable stars.

Ans: TrueLink To: The Variety of StarsDifficulty Level: Easy

31. A main sequence star in the H-R diagram is in the hydrogen burning stage of its existence.

Ans: TrueLink To: The Life Cycles of StarsDifficulty Level: Easy

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32. A star balances the forces of gravity against the high temperature and pressure of nuclear fires in the stellar core.


33. The degeneracy pressure of electrons is usually measured at the earliest stage of a star’s existence.


34. A star will start its existence as a white dwarf and end as a red giant.


35. A neutron star is dense and small, compared to the Sun.


36. The supernova 1987A contradicted all the theories of stellar evolution proposed up to that time.


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37. What are the two factors that affect the behavior of every star?

Ans: Mass and age.Link To: The Variety of StarsDifficulty Level: Easy

38. The iron in your blood was made duringa. a chemical process that occurred during Earth's formation.b. the final moments in the life of a small star.c. fusion during our Sun's creation.d. fission reactions during the Big Bang.e. the nuclear burning of a very large star.

Ans: eLink To: The Life Cycles of StarsDifficulty Level: Medium

39. If you were describing the structure of the Sun correctly, you would say thata. ten percent of the total volume of the Sun is the core.b. the Sun’s outer region is a convection zone.c. the photosphere thins away from the Sun's surface.d. a gaseous chromosphere and corona are visible only during a solar eclipse.e. All of the above are true.

Ans: eLink To: The Anatomy of StarsDifficulty Level: Medium

40. Why do astronomers prefer orbiting telescopes over Earth-based telescopes?a. lower user costs and more research time optionsb. exciting space travel possible for observationsc. wider range of electromagnetic wavelengths detectedd. greater international cooperatione. more aesthetically pleasing

Ans: cLink To: The Nature of StarsDifficulty Level: Medium

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41. It is impossible to extract energy from iron by fusion or fission.

Ans: TrueLink To: The Life Cycles of StarsDifficulty Level: Medium

42. Why are new stars made of hydrogen gas?

Ans: Hydrogen gas is the simplest and the most common material in space.Link To: The Life Cycles of StarsDifficulty Level: Medium

43. What is the difference between apparent brightness and absolute brightness in star classification?

Ans: Apparent brightness is relative brightness when viewed from Earth with distant stars appearing dimmer. Absolute brightness is a measure of stellar brightness from a standard distance.Link To: The Variety of StarsDifficulty Level: Medium

44. Compare the process of hydrogen burning with helium burning in a star.

Ans: After the hydrogen fuel in the core of a star is depleted, the star will contract under the force of gravity. At the same time the temperature will rise in the core until helium is fused to form carbon. Helium burning is the final stage in a star's life that produces energy. Link To: The Anatomy of StarsDifficulty Level: Medium

45. Why do scientists believe that black holes exist, since black holes cannot be seen and none have ever been confirmed in space?

Ans: Black holes give off a particular radiation signature; objects around the black hole behave in a particular manner.Link To: The Life Cycles of StarsDifficulty Level: Medium

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46. From an observer’s point of view, how would the birth of a star appear different from the death of a large star (supernovae)?

Ans: These events are similar in that they both expel a shell of material although the supernova is more dramatic. These events are different in that the new star emits continuous light whereas the dying star fades to black.Link To: The Life Cycles of StarsDifficulty Level: Medium

47. From the perspective of Earth, how are neutron stars and pulsars the same and how are they different?

Ans: They are actually the same object; pulsars are only neutron stars whose poles are pointing toward the Earth.Link To: The Life Cycles of StarsDifficulty Level: Medium

48. Why are imaginary space creatures often depicted as havingeyes larger than those of Earth dwellers? Compare the “eyes” of a Venusian with the “eyes” of a Plutonian.Science fiction writers and illustrators may be enlarging

Ans: the eyes of extraterrestrials to indicate their need to collect more photons, similar in the theory explaining the large eyes of nocturnal animals. Following that logic, Venusian “eyes” would be smaller than those of the Plutonians.Link To: The Anatomy of StarsDifficulty Level: Hard

49. What is the answer to the solar neutrino problem?

Ans: Experiments before 2001, designed to measure the number of neutrinos given off by the Sun, had detected fewer neutrinos than expected. Scientists hypothesized that the ordinary electron neutrinos were converted to other types of neutrinos during theirtransit to Earth. The "lost" neutrinos were recently detected in an experiment comparing neutrino capture in pure water versus heavy water. Heavy water will only react with the electron neutrino.

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Pure water will react with all kinds of neutrinos. One-third of the neutrinos are ordinary electron neutrinos; two-thirds have been converted.Link To: The Anatomy of StarsDifficulty Level: Hard

50. List the events in the life of a Sun-like star in chronological order. Will the star becomes a supernova? Why or why not?

Ans: It is a part of a concentration of mass in a cloud of gas and debris. It becomes a plasma made mostly of protons and electrons. Hydrogen is burned in the star’s core.The star collapses temporarily. The star expands and becomes a red giant. The star shrinks to become a white dwarf.Link To: The Life Cycles of StarsDifficulty Level: Hard

51. What four aspects of photons are measured by astronomers and what instruments do the scientists use?

Ans: Astronomers measure photon wavelength with spectroscopy; photon intensity with light meters; photon direction by recording two angles; and the variation of wavelength, intensity, and position over time.Link To: The Nature of StarsDifficulty Level: Hard

52. Explain how the Northern Lights are formed.

Ans: The Northern Lights, also called the Aurora Borealis, are flashing colored lights seen in the Earth’s night sky at high northern latitudes when the ions forming the solar wind interact with the Earth's magnetic field in the outer reaches of the Earth’s atmosphere. Link To: The Nature of StarsDifficulty Level: Hard

53. How can the ashes of one stellar nuclear fire become the fuel for the next stellar nuclear fire?

Ans: In medium size stars, hydrogen is burned in nuclear fusion reactions to form helium and, in the later stages, the helium ash is burned to produce carbon. The carbon itself cannot ignite in stars the size of our Sun. In very large stars, the pressure in the cores is sointense that the carbon can be changed by fusion into even larger nuclei like oxygen and silicon.Link To: The Life Cycles of StarsDifficulty Level: Hard

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54. Why do larger stars have shorter life spans?

Ans: Larger stars may have more hydrogen fuel to burn but have shorter life spans, when compared with small or average size stars. The reason is that large stars must burnhydrogen at rates many times greater than that of smaller stars to overcome the intense force of gravity caused by the star’s massiveness.Link To: The Life Cycles of StarsDifficulty Level: Hard

55. How are naturally occurring elements heavier than iron formed in stellar processes?

Ans: Elements heavier than iron are created when a very large star explodes in a supernova, sending out shockwaves. This raises the temperature and causes collisions of nuclei, which forms new elements.Link To: The Anatomy of StarsDifficulty Level: Hard

56. How are Cepheid variables used to classify stars?

Ans: The distance a star is from the Earth can be determined with triangulation (for nearby stars) or with Cepheid variables. The Cepheid variable stars are standards of comparison for stars greater than a few hundred light-years away using known values of energy output from the star and energy received by Earth. Distance is calculated from comparable brightness (magnitude).Link To: The Variety of StarsDifficulty Level: Hard

57. What advantages might there be to living inside a Dyson Sphere? What would be the limitations future scientists must face before constructing a Dyson Sphere?

Ans: A Dyson sphere would not only intercept and utilize all of a star’s energy, it also could support a tremendous population. Such an immense structure would have an internal surface area comparable to more than 500 million Earth-like planets, and it would be uniformly heated in eternal daylight.Link To: The Anatomy of StarsDifficulty Level: Hard

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58. How are the original telescopes different from modern telescopes? How do the former improve upon the latter?

Ans: Answers will vary but could include facts about early telescopes using only light whereas modern, non-optical telescopes use other sources of energy to ‘see’ distant objects. Modern non-optical telescopes can be used 24 hours a day, in good weather or bad. Modern optical telescopes have technological advances such as better glass grinding, computer operations, etc.Link To: The Nature of StarsDifficulty Level: Hard

59. When pulsars were first detected, they were called LGM, which stood for Little Green Men. What characteristic of pulsars might have caused astronomers to give them this name?

Ans: Answers will vary but should include reference to the regular pulse rate that appeared as if someone controlled the projection of energy.Link To: The Life Cycles of StarsDifficulty Level: Hard

60. If the Sun had not burned fairly evenly since the creation of the Earth, how would life on Earth be different?

Ans: Answers will vary but could include plant and animal adaptations, different abundances of elements, and so forth.Link To: The Nature of StarsDifficulty Level: Hard

61. If a new star were discovered, what characteristics would it have to have in order to be identified as a main sequence star?

Ans: Medium size, temperature, color.Link To: The Life Cycles of StarsDifficulty Level: Hard

62. During ocean voyages, early sailors used a method called triangulation to determine the location of their ships. How is this same method used today by astronomers to determine the distance to certain neighboring stars?

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Ans: By measuring the angle of sight to a given star from two points of known separation, we can determine the star’s distance from us.Link To: The Anatomy of StarsDifficulty Level: Hard

63. Evaluate the positive and negative aspects of using a star as an energy source as proposed by the construction of a Dyson Sphere.

Ans: Positive: a source of energy lasting billions of yearsNegative: what to do with the solar wind particles and what happens if the star changes energy output—even by 1-2%?Link To: The Anatomy of Stars Difficulty Level: Hard

64. We don’t often see stars in the daytime, but if you dug a hole deep enough could you see the stars from the bottom?

Ans: Yes, but it would be a hole tens of miles deep.Link To: The Anatomy of StarsDifficulty Level: Hard

65. If some one says to you, “all stars are the same—just tiny points of light”, how might you convince them they have different temperatures (color) and different magnitudes (brightness).

Ans: Answers will vary, however, the human eye is not good at discriminating color at low light levels, but a color photograph can illustrate different colors. As for brightness, light bulbs of the same wattage placed at different distances (or varying wattages placed at the same distances) can illustrate magnitude.Link To: The Variety of StarsDifficulty Level: Hard

66. In the 1800s scientists knew that if the Sun was composed of conventional fuels (coal, oil, wood) it would have a burning life of only a few thousand years at best. How might this information impact the debate of “how old is the Earth” in that era?

Ans: Either the Earth is only a few thousand years old or the Sun is using a different source of fuel—one with a greater lifetime.Link To: The Nature of Stars

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Difficulty Level: Hard

67. If the Earth had evolved around a different star—a redder star that produced more frequencies in the infrared and microwave bands—how might plant and animal development been altered to respond to these frequencies?

Ans: Answers will vary but for sure if eyes developed they would have to be much larger to receive these longer frequencies. Plants would have evolved chlorophyll that responded to different wavelengths than that of green light.Link To: The Anatomy of StarsDifficulty Level: Hard

68. What elements on the periodic table are the products of supernovae? Why would this be true?

Ans: All elements heavier than iron are formed as a result of higher temperatures and pressures generated by larger stars when they undergo a catastrophic gravitational collapse.Link To: The Life Cycles of StarsDifficulty Level: Hard

69. How is it that optical telescopes are placed in orbit but radio telescopes are not?

Ans: The visible spectrum frequencies are distorted and absorbed by the atmosphere but radio waves pass through relatively undisturbed.Link To: The Nature of StarsDifficulty Level: Hard

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Documents

stars difficulty level

stellar nuclear fire

main sequence star

cepheid variable stars

shorter life spans

ordinary electron neutrinos

radio waves

neutron stars