Download PH109 Exploring the Universe, Test#4, Spring 2005 Please indicate

PH109 Exploring the Universe, Test#4, Spring 2005
Please indicate the best answer to the following questions on the answer sheet provided.
1. Most of the mass of a galaxy is
a. contained in the massive O and B stars in the galaxy.
b. contained in the H I regions of the galaxy.
c. contained in the H II regions of the galaxy.
d. contained in the dark matter of the galaxy.
2. The mass of a single galaxy might be found by
a. the double galaxy method, b. the rotation curve method, c. the cluster method. d. any of these
3. 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.
4. The two dwarf irregular companions of the Milky Way Galaxy are known as the
a. bi-polar nebular, b. M31 and M32, c. Happy and Sleepy, d. large and small Magellanic clouds
5. 21 cm radiation is produced by which element?
a. hydrogen, b. helium, c. carbon, d. iron
6. 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
7. What is the name of the nearest large galaxy to our own
a. Milky Way, b. Andromeda, c. Orion, d. Cygnus
8. Hubble’s law states that:
a. putting telescopes in space will cost approximately ten times more
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
9. What type of galaxy is the Andromeda galaxy M31?
a) spiral, b) globular, c) elliptical, d) irregular
10. 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
11. The radio emission from radio galaxies and quasars is due to
a) thermal emission, b) blackbody radiation, c) O and B stars, d) synchrotron radiation
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. 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
14. Why is the energy source of active galaxies thought to be extremely compact?
a) Their energy is totally no stellar in origin.
b) Their spectra are like those produced by ordinary stars.
c) They vary on rapid time scales.
d) They can be seen clearly; we can see that the energy source is compact.
15. 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
16. Quasars were originally discovered as
a) strong radio sources identified with star-like images on photographs
b) variable sources of light
c) bright galaxies, and only later found to be radio sources
d) the only type of radio source within our galaxy
17. Which type of galaxy contains the least amount of interstellar material?
a) Ellipticals, b) spirals, c) barred spirals, d) irregulars
18. A primary difference between spiral and elliptical galaxies is
a) all ellipticals are more massive than spirals
b) ellipticals have more extensive interstellar media than spirals
c) star formation has ceased in ellipticals, but not in spirals
d) spirals have more stars than ellipticals
19. Why do the cores of spiral galaxies appear redder than the arms
a) because of reddening due to dust, b) because the cores are bigger
b) because the cores are further away, d) because of black holes in the center
20. The distribution of galaxies in the universe
a) follows the same distribution as stars, b) arraigned on the surfaces of giant bubbles or voids
c) fairly uniform, d) has remained the same as it was during the big bang
21. 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
22. 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
23. 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
24. How was Hubble able to determine the distances of nearby galaxies?
a) by using radar
b) by measuring trigonometric parallaxes
c) by measuring the typical angular separations of stars in them
d) by observing Cepheid variables in them
25. Which of these objects are not found in the Galactic Halo?
a) RR Lyrae variables ,b) globular clusters,c) emission nebulae ,d) stars with comet-like orbits
26. In the formation of our Galaxy, the ________ formed first.
a) galactic disk ,b) galactic center ,c) globular clusters, d) spiral arms
27. What good are 21 cm radio waves to galactic astronomers?
a) They cut through the dusty cocoons to let us watch star birth.
b) We can reflect them off the core of the Galaxy.
c) Their Doppler shifts let us map the motions and locations of spiral arms.
d) They bounce off stars like our Sun to let us precisely measure their distances.
28. Why are the supermassive giant ellipticals found at the centers of the rich galaxy clusters?
a) Most of the matter forming the cluster fell to the center at the beginning.
b) In the beginning, its mass attracted the smaller nearby galaxies to form the cluster.
c) The concentration of dark matter dictated this.
d) Such giants are the result of many mergers, cannibalizing smaller neighbors.
29. Based on galactic rotation curves and cluster dynamics, we think dark matter:
a) is a minor component of the entire mass of the universe.
b) is best detected from the x-rays it produces in the intergalactic medium.
c) will have no effect on the fate of the universe.
d) comprises over 90% of the entire mass of the universe.
30. Which of these astronomers first related speeds and distances for galaxies?
a) Harlow Shapley , b) Edwin Hubble , c) Vesto M. Slipher , d) William Herschel
31. 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
32. 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
33. 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
34. 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
35. 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
36. Which type of galaxy contains the least amount of interstellar material?
a) Ellipticals, b) spirals, c) barred spirals, d) irregulars
37. 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
38. 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
39. What type of galaxy is frequently found at the center of a rich cluster of galaxies?
a) elliptical, b) spiral, c) barred spiral, d) irregular
40. 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