BROCK UNIVERSITY. Test 2, March 2015 Number of pages: 9 Course: ASTR 1P02 Number of Students: 420 Date of Examination: March 5, 2015

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1 BROCK UNIVERSITY Page 1 of 9 Test 2, March 2015 Number of pages: 9 Course: ASTR 1P02 Number of Students: 420 Date of Examination: March 5, 2015 Number of hours: 50 min Time of Examination: 18:00 18:50 Instructor: B.Mitrović 1. A spiral galaxy has a small bright central region, and the intensity of its radiation varies on time scale of minutes. It is most likely galaxy. (a) barred spiral (b) radio (c) Seyfert (d) irregular 2. From what evidence do astronomers deduce that the Universe is expanding (a) They can see the disks of galaxies getting smaller over time. (b) They can see the edge of the Universe moving away from us. (c) They see a redshift in the spectral lines of distant galaxies. (d) They can see distant galaxies dissolve, pulled apart by the expansion of space. 3. Irregular galaxies are the brightest galaxies in the Universe. 4. The redshift of spectra emitted by the distant galaxies is caused by (a) the Doppler effect. (b) gravitational redshift. (c) cosmological redshift. 5. Elliptical galaxies contain a lot of gas and dust. 6. When two galaxies collide all of their stars are destroyed in star-star collisions. 1

2 Course: ASTR1P02 Date: March 5, 2015 page 2 of 9 pages 7. Astronomers think that spiral arms form because (a) of shock waves from the black hole at the center of the galaxy. (b) younger stars travel more slowly than older stars. (c) density waves create a stellar pileup. (d) dust and gas do not orbit at the same speed as the stars. 8. Which one of these two types of elliptical galaxies deviates more from spherical shape? (a) E1. (b) E7. 9. Astronomers think that the dark matter exists because (a) they can detect it with radio telescopes. (b) the expansion rate of the universe is increasing. (c) the stars in galaxies rotate faster than expected based on visible matter in them. 10. The size of the region responsible for large luminosity of a quasar can be estimated from (a) its distance. (b) the period of its luminosity variation. (c) its redshift. (d) its mass. 11. Astronomers have determined the mass of the supermassive black hole at the center of the Milky Way by (a) measuring its Schwarzschild radius R S against background stars and then using R S = 3M to determine its mass M. (b) measuring its energy output in the form of X-rays. (c) measuring orbital data (distance and speed) of stars orbiting it. (d) [There is no supermassive black hole at the center of our galaxy.] 12. The distance of galaxy A is three times the distance of galaxy B. The recession speed of A is the recession speed of galaxy B. (a) three times (b) one third of 2

3 Course: ASTR1P02 Date: March 5, 2015 page 3 of 9 pages 13. A galaxy has a bright linear feature in its central region. What kind of galaxy is it most likely to be? (a) Spiral. (b) Barred Spiral. (c) Elliptical. (d) Irregular. 14. A large galaxy contains mostly old Population II stars spread smoothly throughout its volume, but it has little dust or gas. What type of galaxy is it most likely to be? (a) Spiral. (b) Barred Spiral. (c) Elliptical. (d) Irregular. 15. Rich galaxy clusters consist mostly of (a) spiral Sc galaxies. (b) barred spiral galaxies. (c) elliptical galaxies and Sa spirals. (d) active galaxies. 16. Galaxies in rich galaxy clusters are more likely to collide than the galaxies in poor galaxy clusters. 17. Observation of elliptical galaxies with multiple nuclei is taken as the evidence for (a) the density wave theory. (b) galaxy mergers. (c) the general theory of relativity. (d) [There are no elliptical galaxies with multiple nuclei.] 18. The expansion rate of the Universe has been increasing ever since the Big Bang. 3

4 Course: ASTR1P02 Date: March 5, 2015 page 4 of 9 pages 19. Astronomers use Cepheid variables to measure (a) rotation curves of galaxies. (b) velocities of galaxies. (c) distances to nearby galaxies. (d) masses of galaxies. 20. The Milky Way belongs to a rich galaxy cluster. 21. Which distance indicators were used to determine the distances of the most distant galaxies in the Universe? (a) Cepheids. (b) Globular clusters. (c) Parallax shifts. (d) Type Ia supernovae. 22. The cosmic microwave background radiation obeys the Wien s/blackbody radiation law. 23. The cosmic microwave background radiation was first observed by (a) Vesto Slipher. (b) Edwin Hubble. (c) Arno Penzias and Robert Wilson. (d) Harlow Shapley. 24. The age of the universe can be estimated from the Hubble s law. 4

5 Course: ASTR1P02 Date: March 5, 2015 page 5 of 9 pages 25. Who was the first to measure the speeds of nearby galaxies? (a) Vesto Slipher. (b) Edwin Hubble. (c) Arno Penzias and Robert Wilson. (d) Harlow Shapley. 26. What evidence supports the Big Bang theory? (a) Massive black holes in galactic centers. (b) Clustering of galaxies. (c) Low intensity microwave radiation from all directions. (d) Quasars. 27. The Hubble s law is consistent with the expansion of the Universe/spacetime. 28. Which of these spiral galaxies contains the highest amount of gas and dust? (a) Sa. (b) Sb. (c) Sc. 29. Which of the following Cepheid variables has the highest peak luminosity? (a) A Cepheid with the period of luminosity variation equal to 3 days. (b) A Cepheid with the period of luminosity variation equal to 10 days. (c) A Cepheid with the period of luminosity variation equal to 30 days. (d) A Cepheid with the period of luminosity variation equal to 50 days. 5

6 Course: ASTR1P02 Date: March 5, 2015 page 6 of 9 pages 30. Astronomers can observe a MACHO using (a) X-ray detectors. (b) gamma-ray detectors. (c) neutrino detectors. (d) gravitational microlensing technique. 31. 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). 32. The globular clusters in the Milky Way are found in (a) the central bulge. (b) the disk. (c) the halo. 33. Associations of hot and luminous stars in the Milky Way are found in (a) the central bulge. (b) the disk. (c) the halo. 34. The diameter of the disk in the Milky Way is about (a) 10,000,000 light-year (ly). (b) 1,000,000 light-year (ly). (c) 100,000 light-year (ly). (d) 10,000 light-year (ly). 35. The value of the cosmological parameter Ω can be deduced from the size and shape of hot and cold regions in the cosmic microwave background radiation. 6

7 Course: ASTR1P02 Date: March 5, 2015 page 7 of 9 pages 36. Since the time of recombination the universe has expanded by about a factor of Recombination of electrons with the nuclei took place when the temperature of the universe dropped to about (a) 300,000 K. (b) 30,000 K. (c) 3,000 K. (d) 300 K. 38. The Universe became transparent to radiation 3 minutes after the Big Bang. 39. The age of the Universe is found to be about 6,000 years. 40. The galaxies with the active galactic nuclei form the majority of galaxies that we observe. 41. If the value of the cosmological parameter Ω was greater than 1 the global curvature of spacetime would be (a) positive. (b) negative. (c) zero. 42. The distance of the Sun from the center of the Milky way is about (a) 3,000,000 light-year (ly). (b) 300,000 light-year (ly). (c) 30,000 light-year (ly). (d) 3,000 light-year (ly). 7

8 Course: ASTR1P02 Date: March 5, 2015 page 8 of 9 pages 43. Sagittarius A is a galaxy in the Local Group. 44. The Sun revolves once around the center of the Milky Way every (a) 2.3 billion years. (b) 230 million years. (c) 23 million years. (d) 2.3 million years. 45. Which of these stars has the highest percentage of elements heavier than hydrogen and helium (so-called metals)? (a) Population I stars. (b) Population II stars. (c) Population III stars. 46. The stars in the halo of the Milky Way are (a) Population I stars. (b) Population II stars. (c) Population III stars. 47. Ourdistancefromthecenter ofthemilkywaywasdeduced fromthedistance ofglobular clusters. 48. The highest concentration of gas and dust in the Milky Way is found in (a) halo. (b) disk. (c) central bulge. 8

9 Course: ASTR1P02 Date: March 5, 2015 page 9 of 9 pages 49. Astronomers deduce that the Milky Way has spiral arms by locating (a) globular clusters. (b) Cepheid variables. (c) associations of hot luminous young stars. (d) sources of infrared radiation. 50. The orbits of stars in the disk of the Milky Way are (a) circular. (b) parabolic. (c) hyperbolic. (d) highly elliptical 9