MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.

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1 Homework Ch 7, 8, 9 Name MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. 1) Our most detailed knowledge of Uranus and Neptune comes from 1) A) the Hubble Space telescope. B) ground-based visual telescopes. C) spacecraft exploration. D) manned missions. E) ground-based radio telescopes. 2) The spacecraft Cassini went into orbit around 2) A) Neptune. B) Saturn. C) Pluto. D) Jupiter. E) Uranus. 3) Small deviations in a planet's orbital motion 3) A) indicate the presence of an extensive atmosphere. B) show the planet's orbit isn't stable. C) imply the nearby presence of a massive body. D) show we don't fully understand gravitational forces yet. E) indicate the presence of a powerful magnetic field. 4) At which planet can the pole remain in darkness for 42 years, then have 42 years of constant daylight? A) Saturn B) Uranus C) Pluto D) Jupiter E) Neptune 4) 5) The reason the jovian planets lost very little of their original atmosphere is due to their 5) A) rapid rotation. B) large mass. C) many moons. D) strong magnetic fields. E) ring systems. SHORT ANSWER. Write the word or phrase that best completes each statement or answers the question. 6) In brightness, Jupiter is second only to the planet most of the time. 6) 7) The most famous and long lasting storm in the solar system is. 7) 8) The oblateness of the jovian planets' disks is caused by their. 8) ESSAY. Write your answer in the space provided or on a separate sheet of paper. 9) In what ways are the magnetic fields of Uranus and Neptune unusual? 10) Contrast the compositions of Jupiter's belts and zones. 1

2 TRUE/FALSE. Write 'T' if the statement is true and 'F' if the statement is false. 11) The thickness of the photosphere is about 100 times the diameter of the Earth, and large sunspots are larger than our whole planet. 11) 12) The Sun's structure is uniform throughout its interior, with no evidence of different layers. 12) 13) The Sun's average density is about the same at Jupiter's, suggesting a similar composition. 13) 14) The solar wind is constantly removing mass from the Sun. 14) MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. 15) What two energy transport mechanisms, in order from outside the core to the surface, are found in the Sun? A) conduction, radiation B) radiation, conduction C) convection, conduction D) conduction, convection E) radiation, convection 15) 16) The outward pressure of hot gas in the Sun 16) A) is cooling the photosphere. B) is increasing the Sun's diameter. C) weakens the magnetic field. D) is balanced by the inward gravitational pressure. E) is responsible for variations in the sunspot cycle. 17) Sunspots are dark splotches on the Sun. Which statement is true? 17) A) They are extremely cold objects, as cold as Pluto. B) They are associated with areas of very low magnetic fields. C) They are hotter than the surrounding areas of the Sun. D) They are extremely hot, but cooler than the surrounding areas of the Sun. E) They are solid bodies floating on the surface of the Sun. SHORT ANSWER. Write the word or phrase that best completes each statement or answers the question. 18) The pattern of hot convective cells rising in the photosphere is called. 18) 19) Stellar spectra tell us that is the second most abundant element in the Sun. 19) 20) The corona can only be glimpsed from Earth during a. 20) 21) Nuclear explains the Sun's immense and sustained energy output. 21) 22) The solar neutrino problem was solved when it was discovered that neutrinos during the time they take to reach the Earth. 22) 2

3 ESSAY. Write your answer in the space provided or on a separate sheet of paper. 23) How might a coronal mass ejection affect Earth? 24) In the proton-proton cycle, two positrons are produced. What more familiar particles are they similar to, and how do they differ? TRUE/FALSE. Write 'T' if the statement is true and 'F' if the statement is false. 25) A parsec is about 3.3 light-years. 25) 26) A parsec is slightly more than 200,000 AU. 26) 27) A +6.0 magnitude star is brighter than a +3.0 magnitude star. 27) 28) A type B star is bluer than a type G star. 28) MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. 29) The H-R diagram can plot 29) A) temperature versus luminosity. B) temperature versus mass. C) radius versus mass. D) radius versus luminosity. E) apparent magnitude versus spectral classes. 30) The stars with masses comparable to our Sun's, but sizes like the Earth are 30) A) blue main sequence stars. B) red giants. C) neutron stars. D) white dwarfs. E) red main sequence stars. 31) In the H-R diagram, what are the two most important types of data plotted? 31) A) luminosities and masses B) absolute and apparent magnitudes C) spectral classes and absolute magnitudes D) sizes and temperatures E) apparent magnitudes and temperatures 32) A star near the lower right of the H-R diagram is likely to be 32) A) red, with high luminosity. B) yellow, with luminosity similar to our Sun's. C) blue, with high luminosity. D) hot, bright, and very large. E) red, with low luminosity. 3

4 33) In what range of masses are most stars found? 33) A) 1 to 3 solar masses B) 0.1 to 2 solar masses C) 0.01 to 100 solar masses D) 0.1 to 100 solar masses E) Stars can have any mass. SHORT ANSWER. Write the word or phrase that best completes each statement or answers the question. 34) To find the distance of nearby stars, we use their parallaxes obtained over -month intervals. 34) 35) If two stars have the same parallax, but the brighter is magnitude +2.3, and the fainter is magnitude +3.3, then the fainter star is less luminous. 35) 36) The absolute magnitude of the Sun is. 36) 37) The ionized helium lines show up only in class stars. 37) 38) In general, the more massive the star, the its lifetime. 38) ESSAY. Write your answer in the space provided or on a separate sheet of paper. 39) How can Betelgeuse be only half the Sun's surface temperature, yet about 10,000 times more luminous than the hotter Sun? 40) How does a star's luminosity relate to its radius and surface temperature? 41) What percentage of stars lie on the main sequence? Why? 42) Explain the difference between radial and transverse velocities. 43) What special type of information is yielded only by eclipsing binary stars? 4

5 Answer Key Testname: HOMEWORK DUE WED 1) C 2) B 3) C 4) B 5) B 6) Venus 7) (Jupiter's) Great Red Spot 8) rapid rotations 9) Unlike the magnetic fields of Earth, Jupiter, and Saturn, the fields of Uranus and Neptune are not aligned with the rotational axis of their planet. Additionally, both fields are offset from their planet's center by a significant amount. 10) The zones are high, cold regions of ammonia ice crystals, white in color. But the lower, warmer belts are brownish from complex chemistry involving hydrogen sulfide, ammonia, and other chemicals. 11) TRUE 12) FALSE 13) TRUE 14) TRUE 15) E 16) D 17) D 18) granulation 19) helium. 20) total solar eclipse 21) fusion 22) oscillate or change into other types of neutrinos 23) If the field lines of a coronal mass ejection are properly oriented, they can potentially disrupt Earth's magnetosphere, causing widespread communications and power disruptions. 24) Positrons are anti-electrons, made of antimatter, and with a positive charge instead of the negative charge of normal electrons. 25) TRUE 26) TRUE 27) FALSE 28) TRUE 29) A 30) D 31) C 32) E 33) D 34) six 35) 2.5 times 36) +5 or +4.8 to be more precise 37) O 38) shorter. 39) It may be cooler, but it is about 1,000 times the Sun's diameter, and has a surface area almost a million times greater than the Sun. 40) As either radius or surface temperature increases, the luminosity also increases. The luminosity is proportional to the square of the radius and the fourth power of the temperature. 41) About 90% of all stars are still fusing hydrogen to helium in their cores. 42) Radial velocity is found from Doppler shifts, and measures speed along our line of sight. Transverse velocity is motion across our line of sight, and requires both the apparent angular proper motion and knowledge of the parallax and distance. 5

6 Answer Key Testname: HOMEWORK DUE WED 43) The analysis of the light curve of eclipsing binaries allows us to measure their sizes. As most are spectroscopic binaries as well, we can use their speeds and durations of various stages of the eclipse to directly measure their diameters. Basically, the longer the eclipse takes, the bigger the star is. 6