PH109 Exploring the Universe test #4, Spring 2007
Please indicate the best answer to the following questions on the answer sheet provided.
1. From the Sun, what is the distance to the Galaxy's center?
a) 8 kpc, b) 30 kpc, c) 300 pc, d) 1000 Ly.
2. Hubble’s law states that:
a) putting telescopes in space will cost approximately ten times more than ground based telescopes
b) the recession of one galaxy must equal the precession of another
c) the faster a galaxy moves away from us the more massive it is
d) the faster a galaxy moves away from us the farther away it is
3. Where do you find young massive stars in a spiral galaxy?
a) in the core, b) on the leading edge of arms, c) on the trailing edge of arms, d) in the halo
4. What kind of galaxy do we live in?
a) Spiral, b) elliptical, c) spherical, d) irregular
5. The size of our galaxy is about
a) 3 light years, b) 120 thousand light years, c) one mega parsec, d) unknown at the present
6. Hubble’s law describes a relationship between a galaxy’s
a) size and brightness, b) number of stars and size, c) shape and age, d) redshift velocity and distance
7. The distribution of matter in a galaxy can be found by measuring
a) the number of stars, b) the rotation curve, c) number of pulsars, d) how thick a galaxy is
8. The location of our Sun in the galaxy is approximately
a) near the core, b) near the outer edge
c) about 2/3 of the way out to the edge, d) not currently determined
9. About how long does it take for the Sun to complete one trip around the galaxy?
a) 25 thousand years, b) 2.5 million years, c) 250 million years, d) 25 billion years
10. A rotation curve for a galaxy is a plot of
a) orbital speed versus distance from center, b) number of rotations versus time
c) orbital distance versus eccentricity, d) temperature versus luminosity
11. How do we know that the quasars are at large distances?
a) they are extremely dim, b) they have large redshifts,
c) they have large parallaxes, d) they are greatly obscured by interstellar dust
12. What is hardest to explain about spiral arm structure
a) that they ever existed in the first place, b) why galaxies only have two of them
c) why they have sharp boundaries, d) how they maintain themselves
13. For what type of object is the period-luminosity relation used for determining distances?
a) Algol variables, b) Cepheids, c) Cataclysmic variables, d) 21 centimeter radiation.
14. Why is our galaxy in the shape of a disk
a) because it rotates
b) because it got sheered off during a galactic collision
c) the outer parts were torn away by the Magallenic clouds
d) the dark matter holds it in that formation
15. If a galaxy is determined to be 2 million light years away, what does that mean
a) it takes light 2 million years to cross the galaxy
b) stars did not turn on till about 2 million years ago
c) it takes light 2 million years to reach us from the galaxy
d) if we could put our galaxy 2 million light years away it would look as bright as that galaxy.
16. The name of the galaxy we live in is
a) Andromeda, b) Virgo, c) Milky Way, d) Smoky Nebula
17. When Galaxies collide
a) their stars collide to form larger stars, b) both galaxies crumple into very dense systems
c) they simply perturb each other’s shape, d) no galaxies are left after the collision
18. An Einstein ring is a
a) group of galaxies which forms a ring in inter-galactic space
b) something Al gave to his mother
c) the theory that say the universe is a continuous ring of space time
d) distortion of an image due to gravitational effects
19. The Magellanic clouds are
a) regions of star formation in the Andromeda galaxy
b) close clusters of galaxies about 10 megaparsecs away
c) nearby irregular galaxies gravitationally bound to the Milky Way
d) an optical illusion caused by dust in the interplanetary medium
20. The 21 cm radiation form Hydrogen is observed by:
a) optical telescopes, b) radio telescopes, c) X-ray telescopes, d) neutrino telescopes
21. Which of the following is not a characteristic of the stars of the disk component of our galaxy?
a. circular orbits, b. randomly inclined orbits, c. higher metal abundance
d. young stars, e. star formation regions
22. Our galaxy has two smaller galaxies in orbit around it which are called
a) A and B galaxies, b) polar galaxies, c) red and blue shifts galaxies, d) Magellanic clouds
23. What causes Cepheid variables to vary in brightness?
a) they pulsate, b) eclipses,
c) changes in nuclear energy generation rate, d) obscuration by clouds of dust
24. Where are globular clusters located in the galaxy?
a) in the nucleus, b) in the disk, c) in the spiral arms, d) in the halo
25. The region between stars is:
a) empty, the stars have accreted all the mater, b) filled mostly with gas and dust
c) composed of dark nebulae, d) filled with emission nebulae
26. Which type of galaxy contains the least amount of interstellar material?
a) Ellipticals, b) spirals, c) barred spirals, d) irregulars
27. The period-luminosity relation is critical in finding distances with:
a) planetary nebula, b) trigometric parallaxes,
c) super nova, d) Cepheid variables
28. The nearest comparable galaxy to our own is the
a) Andromeda galaxy, b) Alpha Centari galaxy,
b) Coma galaxy, c) Magellanic galaxy
29. The oldest stars in the galaxy are found
a. in globular clusters in the halo, b. at the center of the galaxy
c. on the front rim of spiral arms, d. in the galactic disk
30. Irregular galaxies have ill defined shape because
a) they rotate too slow to form a disk, b) active star formation disrupts disk
c) too many black holes distort space time, d) recent collisions caused loss of shape
31. The object located at the center of our Galaxy is believed to be a ______.
a) a large cluster of stars, b) an emission nebula c) a black hole, d) a massive supernova
32. As matter streams into a black hole it usually forms what kind of structure
a) accretion disk, b) spherical shell, c) a dark nebula, d) star formation region
33. In the video of the simulation of six galaxies interacting, what was the result
a) they all orbited around each other, b) they drifted away from each other because of the Hubble force
c) they were all cannibalized into one giant galaxy, d) they became neutron galaxies
34. The very rapid orbital speed detected near the center of our galaxy suggests that
a) our galaxy has a lot of stored angular momentum, b) massive stars are at the center
c) a black hole is at the center, d) we have been in a collision in the past
35. An Einstein ring is a
a) group of galaxies which forms a ring in inter-galactic space
b) something Al gave to his mother
c) the theory that say the universe is a continuous ring of space time
d) distortion of an image due to gravitational effects
36. Which of these astronomers first related speeds and distances for galaxies?
a) Harlow Shapley , b) Edwin Hubble , c) Vesto M. Slipher , d) William Herschel
37. Quasars may be caused by
a) directly viewing jets of material from black holes, b) interacting galaxies
c) massive super-nova explosions, d) left over fragments of the big bang explosion
38. The true distribution of galaxies is:
a) randomly placed throughout the universe, b) dependent on the viewing geometry of the observer
c) impossible to figure out, d) grouped in filaments and clusters of galaxies
39. Why can we not use parallax to measure the distances to galaxies
a) they are too far away b) they are too faint c) they are too large d) there are too many of them
40. Which of the following is not found in the Galaxy’s spiral arms?
a) young star clusters, b) O and B stars, c) globular clusters, d) emission nebulae