Astrophysics Exam: Cosmic Elements and Stellar Phenomena

To explain the presence of elements such as calcium in our bodies, the astronomer Carl Sagan famously said “We’re made of star stuff.” Temperature variations in the cosmic microwave background are consistent with a “flat” Universe. Highlight Green If correct Highlight Yellow if unsure Highlight Red if wrong Post questions with the multiple choices then highlight the answer 1.) Temperature variations in the cosmic microwave background are consistent with a “flat” Universe. A.) true b.) false 2.) Once a star has progressed beyond the protostar stage, it enters the H-R diagram Main nSequence and moves along it as it ages. true or False ? 250 Mpc 3.) A galaxy’s spectrum has a red shift, V , of 28,000 km/sec. If the Hubble constant, H 0 , is truly constant and has a value of (70 km/sec)/Mpc, how far away from Earth, D , is the galaxy? a. 250 Mpc

b. 400 Mpc c. 25 Mpc d. 40 Mpc e. 2.5 Mpc As stars orbit the center of the Milky Way they move in and out of the spiral arms. True False Mercury’s lack of an atmosphere is largely attributable to both its weak gravity and its proximity to the Sun. True False 4.) To explain the presence of elements such as calcium in our bodies, the astronomer Carl Sagan famously said "We're made of star stuff". True/ False 5.) If a star has a parallax of 0.02 arc seconds, how far away is it? A. 50 light years b.25 parsecs. C.40 parsecs D. 2 parsecs e.50 parsecs i

9)Davis and Koshiba observed only 1/3 the number of the solar neutrinos they expected because neutrinos come in three oscillating flavors, and their experiments detected only one. 4 True or False 6.) The Sun produces most of its energy from the CNO fusion cycle, in which carbon, nitrogen and oxygen catalyze the fusion of hydrogen into helium. False 7. What causes the radio-frequency pulses of a pulsar? Answer: A spinning neutron star producing a beam of radio-frequency radiation that sweeps through space. When the beam points toward Earth, we observe a pulse The densities of the outer planets are much lower than the densities of the inner planets because a. The inner planets formed a billion years earlier than the outer planets, when there were copious amounts of rock and iron available b. The outer planets are much hotter than the inner planets, causing them to grow in volume, thereby lowering their densities c. The outer planets contain large quantities of light elements, such as hydrogen and helium, which can condense only far away from the Sun

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d. Volcanic eruptions have ejected all the heavier elements that were originally in the cores of the outer planets e. The inner planets are much smaller a. Variations in luminosity of a star due to absorption of radiation by its stellar atmosphere, leading to expansion of the star, followed by cooling and then contraction, with the cycle repeating periodically b. A white dwarf’s binary companion emitting radiation as its mass is “stolen” periodically by the white dwarf c. A spinning neutron star producing a beam of radio-frequency radiation that sweeps through space. When the beam points toward Earth, we observe a pulse d. A star orbiting a black hole close to its event horizon, generating intense radiation that is visible periodically n the star appears in front of the black hole e A collision of two neutron stars 8.) The Cassini Division in Saturn’s ring structure is due to collisions between the moons Enceladus and Mimas. a. True b.) False

9.) Mercury’s lack of an atmosphere is largely attributable to both its weak gravity and its proximity to the Sun. a.) true b.) false 10. Which of the following is NOT correct about Type II supernovas? b.They are the precursors to white dwarfs 11. Why does a galaxy such as M31 (Andromeda) have a blue shift instead of a red shift, which is characteristic of almost all other galaxies? a. It is relatively stationary, but the Milky Way is moving toward it b. It comprises many young, blue stars c. Gravitational lensing by a black hole at its center distorts the light d. It contains no yellow RR Lyraes or red giants e. Gravity and local motion are dominate over the universe’s expansion - All Type II supernovas have the same luminosity.

True False I’m Astronomers think Uranus was hit by a large body early in its history because it orbits the Sun in a direction opposite to the other planets. True False A large galaxy containing mostly old (Pop II) stars spread smoothly throughout its volume but having little dust or gas is most likely an ellip tical galaxy. True False The Kirkwood gaps, which are analogous to the gaps in Saturn’s rings, are found in Jupiter’s cloud patterns. False The Event Horizon Telescope a. Is an instrument on the International Space Station that monitors solar storms b. Comprises eight radio telescopes around the world that captured the image of the accretion disk around the Milky Way’s black hole c. Is a space based instrument at u L2 that observes stellar phenomena visible just over the Earth’s horizon

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d. Is an instrument that was launched in December 2021 and is capable of imaging distant galaxies in the infrared part of the electromagnetic spectrum e. Is the name of a highly successful radio telescope built in the 1960s in Arecibo, Puerto Rico that collapsed in 2020 All of the terrestrial planets have strong magnetic fields True False 12. Astronomers invoke unexplained dark matter to account for the shape of stellar rotation curves. True 13. Differential rotation of the Sun results in b.Complex magnetic fields that periodically snap and cause solar storms 14. Detailed measurements of the red shift of distant galaxies provide evidence that the expansion of the universe is slowing down. False 15 . To explain the presence of elements such as calcium in our bodies, the astronomer Carl Sagan famously said “We’re made of star stuff.” True 16. Venus represents stark evidence of the greenhouse gas effect. True 17. The Sun is supported against the crushing force of its gravity by gas pressure.

True 18. As in the case of the Moon’s proximty to the Earth, Mercury’s proximity to the Sun leads to phase locking of its orbital and rotational periods in a ratio of 1:1; that is, its rotational and orbital periods are equal. True 18. Mercury’s lack of an atmosphere is largely attributable to both its weak gravity and its proximity to the Sun. True 19. The Tip of the Red Giant Branch is of interest because e.It contains stars that serve as standard candles 20. A galaxy’s spectrum has a red shift, V , of 28,000 km/sec. If the Hubble constant, H 0 , is truly constant and has a value of (70 km/sec)/Mpc, how far away from Earth, D , is the galaxy? a. 400 Mpc 21. If a star has a parallax of 0.02 arc seconds, how far away is it? d. 50 parsecs 22. Which of the following information about neutrinos is FALSE?dark b. They are massless. 23. Eddington’s log-log plot of luminosity vs. mass showed that log L was linearly proportional to log M , the straight line having a slope of ~3.5. The plot suggests that a star’s lifetime increases with its mass in accordance with a 3.5 power law. False 24. All of the terrestrial planets have strong magnetic fields False

25. Dark nebulas are e. Clouds of dust that obscure stars behind them. 26. Two stars have the same luminosity but one has a smaller radius than the other. What can you say about them? b. The smaller star has a higher temperature. 27. The Schwarzchild radius is e. The radius of a body at which the escape velocity equals the speed of light. 28. Temperature variations in the cosmic microwave background are consistent with a “flat” Universe. True 29. In a sample of nearby stars, about what percentage will lie OFF the main sequence? D. 10% 30. The Cassini Division in Saturn’s ring structure is due to collisions between the moons Enceladus and Mimas. False 31. As stars orbit the center of the Milky Way they move in and out of the spiral arms. True 32. The densities of the outer planets are much lower than the densities of the inner planets because c. The outer planets contain large quantities of light elements, such as hydrogen and helium, which can condense only far away from the Sun. 33. A large galaxy containing mostly old (Pop II) stars spread smoothly throughout its volume but having little dust or gas is most likely an elliptical galaxy. True

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34. Acoustic waves emanating from Jupiter’s giant red spot are thought to be heating the “upper atmosphere” above it. False 35. According to accepted cosmological principles E. From the very beginning, photons were able to travel through the Universe relatively unimpeded 36. Astronomers think Uranus was hit by a large body early in its history because it orbits the Sun in a direction opposite to the other planets. False 37. What causes the radio-frequency pulses of a pulsar? a. A spinning neutron star producing a beam of radio-frequency radiation that sweeps through space. When the beam points toward Earth, we observe a pulse. 38. The Kirkwood gaps, which are analogous to the gaps in Saturn’s rings, are found in Jupiter’s cloud patterns. False 39. Why does a galaxy such as M31 (Andromeda) have a blue shift instead of a red shift, which is characteristic of almost all other galaxies? d.It is relatively stationary, but the Milky Way is moving toward it 40. Once a star has progressed beyond the protostar stage, it enters the H-R diagram Main Sequence and moves along it as it ages. True

41. From the time since the period of Inﬂation, conditions of the Universe have been c. Much colder than today. 42. All Type II supernovas have the same luminosity. False 43. What is the Chandresakhar limit? a. The maximum mass of a stable white dwarf, above which it will explode as a Type Ia supernova. Measurements suggest the Universe is currently composed of approximately . 72% dark energy, 23% dark matter, 5% regular matter . 4/ A large galaxy containing mostly old (Pop II) stars spread smoothly throughout its volume but having little dust or gas is most likely an elliptical galaxy. A true B/ false

Detailed measurements of the redshift of distant galaxies provide evidence that the expansion of the universe is slowing down. True False The Trojans, the Greeks and the Hildas are no a. The names of moons that orbit Jupiter in retrograde motion b. Star groupings that outline three spiral arms of the Milky Way c. Classes of dwarf galaxies in the Local Group d. The names of meteor showers that occur during March, April and August e. Asteroids clusters that orbit the Sun along with Jupiter \ NASA included the helicopter Ingenuity as part of the Perseverance mission a . To sample the water in the Martian atmosphere ok b . To spy on rovers sent to Mars by other nations c . d. To prove that helicopters could fly in thin atmospheres

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e. To provide logistical support for future Mars missions Eddington’s log-log plot of luminosity vs. mass showed that log L was linearly proportional to log M , the straight line having a slope of ~3.5. The plot suggests that a star’s lifetime increases with its mass in accordance with a 3.5 power law. False The Schwarzchild radius is a. The distance from a planet at which an orbiting moon of the same density will be broken apart due to tidal forces b. The minimum radius a white dwarf can have before it implodes due to gravity c. The maximum radius a neutron star can have and still behave as a pulsar d. The maximum radius a star’s core can have and still support nuclear fusion e. The radius of a body at which the escape velocity equals the speed of light Dark nebulas are a. Clouds of gas surrounding exoplanets b. Stellar remnants of Type II supernovas c. Clouds of dust that obscure stars behind them d. Clouds of dust released when a planet is hit by a large asteroid e. Shells of gas ejected by low-mass stars at the end of their lives c.

The Universe is growing ever more slowly d. All black holes are primordial in origin; that is, they trace their origins back to the era shortly after the Big Bang e. When the Universe underwent a period of rapid inflation shortly after the Big Bang, its size increased faster than the speed of light From the time since the period of Inflation, conditions of the Universe have been. ?? a. Much hotter than today b. Dominated by visible matter c. Much colder than today d. Not very different than today e. Dominated by Compton and Thompson scattering of photons As stars orbit the center of the Milky Way they move in and out of the spiral arms. True False Two stars have the same luminosity but one has a ok smaller radius than the other. What can you say about them? a. The larger star contains more helium than the smaller one b. The smaller star must be rotating faster c. The smaller star has a higher temperature d. The smaller star has larger amounts of radioactive elements, such as uranium The larger star contains more helium than the smaller one e. The larger star has a higher temperature

Acoustic waves emanating from Jupiter’s giant red spot are thought to be heating the “upper atmosphere” above it. True False Venus represents stark evidence of the greenhouse gas effect True False 6) According to accepted cosmological principles a. From the very beginning, photons were able to travel through the Universe relatively unimpeded b. The Universe is infinite in size c. The Universe is growing ever more slowly

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d. All black holes are primordial in origin; that is, they trace their origins back to the era shortly after the Big Bang e. When the Universe underwent a period of rapid inflation shortly after the Big Bang, its size increased faster than the speed of light The Sun produces most of its energy from the CNO fusion cycle, in which carbon, nitrogen and oxygen catalyze the fusion of hydrogen into helium. True False All of the terrestrial planets have strong magnetic fields O True False Which of the following information about neutrinos is FALSE? They are massless Mercury’s lack of an atmosphere is large attributable to both it weak gravity and its proximity to the sun. True In a sample of nearby stars, about what percentage will lie OFF the main sequence? 10%

What is the Chandresakhar limit? The maximum mass of a stable white dwarf, above which it will explode as a Type Ia supernova Temperature variations in the cosmic microwave background are consistent with a “flat” Universe. True False

Astro exam 2

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