BROCK UNIVERSITY. Test 2, March 2018 Number of pages: 9 Course: ASTR 1P02, Section 1 Number of Students: 465 Date of Examination: March 12, 2018

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1 BROCK UNIVERSITY Page 1 of 9 Test 2, March 2018 Number of pages: 9 Course: ASTR 1P02, Section 1 Number of Students: 465 Date of Examination: March 12, 2018 Number of hours: 50 min Time of Examination: 17:00 17:50 Instructor: B.Mitrović 1. Cepheid variable A has the period of luminosity variation twice that of Cepheid variable B. (a) The peak luminosity of A is smaller than the peak luminosity of B. (b) The peak luminosity of A is larger than the peak luminosity of B. (c) [No conclusion can be made.] 2. Harlow Shapley determined our position relative to the galactic center by measuring (a) the distances of open clusters of stars. (b) the distances of globular clusters. (c) the distances of star associations. 3. The period-luminosity relation for Cepheid variables was discovered by (a) Edwin Hubble. (b) Vesto Slipher. (c) Harlow Shapley. (d) Henrietta Leavitt. 4. Harlow Shapley used to measure the distances in the Milky Way. (a) spectroscopic parallax (b) the Doppler shift of starlight (c) Cepheid variables (d) stellar parallax 5. The spiral arms of a galaxy move faster than its stars. 1

2 Course: ASTR1P02 Date: March 12, 2018 page 2 of 9 pages 6. The clusters of stars in the halo of the Milky Way are (a) the star associations. (b) the open clusters. (c) the globular cluster. 7. The spiral arms of the Milky Way are outlined by (a) the Sun-like stars. (b) the hot, young, luminous stars. (c) the Population II stars. (d) the Population III stars. 8. The disk stars of the Milky Way are mostly (a) Population I stars. (b) Population II stars. (c) Population III stars. 9. The halo stars of the Milky Way are mostly (a) Population I stars. (b) Population II stars. (c) Population III stars. 10. The oldest stars in the Milky Way are found mostly in (a) the halo. (b) the disk. 11. Which stars contain the highest amounts of elements heavier than helium? (a) Population I stars. (b) Population II stars. (c) Population III stars. 2

3 Course: ASTR1P02 Date: March 12, 2018 page 3 of 9 pages 12. The Sun revolves once around the galaxy in 230 million ( ) years. How many times did the Sun revolve around the galaxy since its formation 4.6 billion ( ) years ago? (a) 10 times. (b) 20 times. (c) 30 times. (d) 40 times. 13. The orbits of Halo stars are (a) circular. (b) parabolic. (c) hyperbolic. (d) highly elliptical. 14. The radius of the orbit of the Sun around galactic center is about (a) 300 light-years. (b) 3,000 light-years. (c) 30,000 light-years. (d) 300,000 light-years. 15. Who was the first to introduce the concept of dark matter based on high speeds of galaxies in a galaxy cluster? (a) Vera Rubin. (b) Albert Einstein. (c) Edwin Hubble. (d) Fritz Zwicky. 16. As a black hole passes between us and a star the star s brightness as a result of gravitational microlensing. (a) decreases. (b) increases. 3

4 Course: ASTR1P02 Date: March 12, 2018 page 4 of 9 pages 17. MACHO account for of the dark matter. (a) 30% (b) 50% (c) 90% 18. Which of the following is not a candidate for MACHO? (a) Black hole. (b) Neutron star. (c) Brown dwarf. (d) Old white dwarf. (e) neutralino. 19. WIMP are assumed to interact with ordinary matter particles only via (a) the electromagnetic force and the gravitational force. (b) the weak nuclear force and the gravitational force. (c) the strong nuclear force and the gravitational force. 20. As of today, no experiments have found WIMP. 21. The observed orbital speeds of stars near the edge of a spiral galaxy decrease with increasing distance from the galactic center. 22. Which distance indicators are used to determine the distances of the most distant galaxies in the Universe? (a) Cepheids. (b) Globular clusters. (c) Type Ia supernovae. (d) Type II supernovae. 4

5 Course: ASTR1P02 Date: March 12, 2018 page 5 of 9 pages 23. The cosmological redshift is caused by (a) the Doppler effect. (b) gravity. (c) the expansion of the Universe. 24. The greater the distance of a galaxy, the smaller is the observed redshift of its spectrum. 25. If you lived in a galaxy far away from the Local Group, your redshift measurements would show that galaxies move (a) away from you in the same way as observed from the Milky Way. (b) away from the Milky Way but toward you. (c) toward you out to the distance of the Milky way; away at larger distances. (d) toward you in half the sky, away in the other half. 26. The distance of galaxy A is ten times the distance of galaxy B. The observed recession speed of A is the observed recession speed of galaxy B. (a) ten times (b) one tenth of 27. The age of the Universe estimated from the Hubble s law (so-called Hubble s time) is equal to (a) the reciprocal of the Hubble s constant (1/H). (b) Hubble s constant H. 28. The Hubble s law is consistent with the expansion of the Universe/spacetime. 29. The center of our galaxy is in the direction of constellation (a) Gemini. (b) Pisces. (c) Sagittarius. (d) Virgo. 5

6 Course: ASTR1P02 Date: March 12, 2018 page 6 of 9 pages 30. How long does it take the radio waves produced by Sagittarius A (or Sgr A ) to reach us on Earth? (a) 300 years. (b) 3,000 years. (c) 30,000 years. (d) 300,000 years. 31. Which of these galaxies make up the majority of brighter galaxies that we observe? (a) Elliptical. (b) Spiral. (c) Irregular. 32. Which of these galaxies contain the least amount of visible gas and dust? (a) Elliptical. (b) Spiral. (c) Irregular. 33. A spiral galaxy has a very large nucleus and hardly visible spiral arms. What type of spiral is it? (a) S0. (b) Sa. (c) Sb. (d) Sc. 34. A spiral galaxy is bluish in color. What type of spiral is it? (a) Sa. (b) Sb. (c) Sc. 35. Which of these galaxies contain the least amount of gas and dust? (a) Sa. (b) Sb. (c) Sc. 6

7 Course: ASTR1P02 Date: March 12, 2018 page 7 of 9 pages 36. Elliptical galaxies consist mostly of (a) Population I stars. (b) Population II stars. (c) Population III stars. 37. Which of these galaxies has the smallest central bulge? (a) Sa. (b) Sb. (c) Sc. 38. The Milky Way galaxy and the Andromeda galaxy are moving away from each other. 39. Elliptical galaxies and Sa spirals are more common in rich galaxy clusters. 40. Seyfert galaxies are (a) elliptical galaxies. (b) spiral galaxies. (c) irregular galaxies. 41. A large percentage of galaxies that we observe are active galaxies. 42. The size of the region responsible for large luminosity of a Seyfert galaxy can be estimated from (a) its luminosity and temperature. (b) its redshift. (c) the period of its luminosity variation. 7

8 Course: ASTR1P02 Date: March 12, 2018 page 8 of 9 pages 43. The nuclei of active galaxies are thought to be powered by matter falling into extremely massive black hole. 44. What evidence supports the Big Bang theory? (a) Low intensity microwave radiation from all directions. (b) Massive black holes in galactic centers. (c) Clustering of galaxies. (d) Quasars. 45. When did the Universe became transparent to light after the Big Bang? (a) When the first nuclei of helium were fused. (b) When the first stars were formed. (c) When the temperature dropped enough so that electrons and protons could combine into neutral hydrogen atoms (so-called recombination). (d) When the temperature dropped enough so that the molecules of hydrogen were formed. 46. Which of the following is important for explaining why the sky is not bright at night. (a) Dust in our galaxy blocks the light from distant galaxies. (b) There are no stars beyond a distance of about 10 million light-years. (c) The Sun has set. (d) The Universe has a finite age. 47. At present the value of parameter Ω resulting from ordinary matter, dark matter and dark energy is (a) less than 0.1 (i.e. the Universe has a negative curvature). (b) equal to 1 (i.e. the Universe is flat). (c) greater than 10 (i.e. the Universe has a positive curvature). 48. At present, the expansion rate of the Universe is (a) increasing. (b) decreasing. (c) constant. 8

9 Course: ASTR1P02 Date: March 12, 2018 page 9 of 9 pages 49. The concept of dark energy is introduced to explain (a) high speed with which galaxies in a cluster orbit each other. (b) the microwave background radiation. (c) high speed of stars near the edges of spiral galaxies. 50. The effective temperature of the microwave background radiation at the present time is the temperature of radiation whan the Universe became transparent to it. (a) higher than (b) lower than (c) the same as 9