midterm exam3 Astronomy102 spring07 - ASTRONOMY 102...

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Unformatted text preview: ASTRONOMY 102 MID-TERM EXAMINATION III 1) Where, in the Milky Way, is the sun? a) halo b) nucleus 0) between 2 spiral arms d) spiral arm e) edge of disk 2) About how many visible stars does the Milky Way contain? a) 100,000 b) 50 c) 10A11 d) 1008 e) 10013 3) In what direction would you look to see the nucleus of the Milky Way? Towards a) Sagittarius b) Big Dipper c) Aries (1) Orion e) Lyra 4) Roughly how many times from now on will the solar system revolve about the center of the galaxy before the sun becomes a red giant? a) 1000 b) 200 c) 20 d) 40 e)100 5) Only about 1/20 th of the mass of the Milky Way is in the form of visible matter. The rest is likely to be a) old n'stars b) WIMPs c) MACHOs d) supersymmetric particles e) all of these 6) How old is the Milky Way? a) 13 x 10"9 yrs b) 13.7 x 10"9 yrs c) 300,000 yrs (1) 5 x 10"9 yrs e) 20 x 10"9 yrs '7) Globplar clusters typically contain a) hot young blue stars b) old red stars c) mostly main seq. stars (1) mostly small stars, like the sun e) a mixture of everything 8) What characterizes a spiral galaxy, compared to an elliptical or irregular? a) well-defined rotation b) always big V c) disk with spiral arms d) massive nucleus with black holes e) all of these 9) An SBc galaxy has a) large nucleus and several spiral arms b) small nucleus and several spiral arms 0) large barred nucleus and 2 spiral arms d) small barred nucleus and 2 spiral arms e) it looks just like the nucleus of a galaxy, with no arms 10) Astronomers believe galaxies are immersed in a huge halo of dark matter. The evidence comes from looking at a graph of stars velocities, V, versus distance from center of the galaxy, r. Which graph indicates the existence of dark matter? 30"! b) T e) V' ' r- P d ) Li: ev i: l— r 11) The nucleus of the Milky Way contains a huge variety of stars. To What do astronomers attribute this? a) nucleus is old b) nucleus is young and active c) nucleus is expanding d) collisions between galaxies e) nucleus is collapsing under gravity 12) A particular absorption line due to Na is red-shifted in a star’s spectrum. In the lab, this line has wavelength 600 nms. In this star the wavelength appears to be . a) 600 nms b) > 600 nms c) < 600 nms 13) Suppose the Hubble constant is measured to be {100 kms/sl‘lMpc, and the recessional speed of a distant galaxy is 10A4 kms/s. How far away is the galaxy? a) 10/8 pc b) 100 pc c) 10"12 pc (1) 3.26 pc ) e fth abo e non o e ve \04 ,2 Cl I DO 14) Radio galaxies are usually a) ellipticals b) spirals c) irregulars . 15) Seyfert galaxies are usually a) ellipticals b) spirals c) irregulars 16) What is the distinctive characteristic of quasars? a) high redshift b) pulsates in radio spectrum c) cannot observe in visible spectrum d) have weak magnetic fields e) move towards us very fast 17) The CBR is a relic from the time when a) Big Bang occurred b) atoms formed c) nuclei formed d) galaxies formed e) Universe became matter dominated 18) If 2 particles were separated by 20 cms the instant the Universe became matter dominated, how far apart would they be after 1 yr? a) 20 kms W M d) 1.1 kms e) 4100 kms 19) If 2 points were separated by 20 cms the instant the Universe became radiation dominated, how far apart would they be after 1 yr? a) 20 kms b) 20 cms c) 20 m d) 1.1 kms e) 4100 kms 20) The existence of which particular nucleus lends strong evidence to the Big Bang scenario? a) H b) D c) Fe d) U e) Co 21) If there was a phase transition in the early Universe, in which GUTs broke down, what happened? a) the elementary forces became equally strong b) all particles became massless 0) some particles gained mass d) Universe became transparent to light e) Universe became opaque 22) The Universe is matter dominated and 13.7 billion years old. What is the Hubble constant? a) 71 (kms/s)/Mpc b) 107 (kms/s)/Mpc c) 50 (kms/s)/Mpc d) 100 (kms/s)/Mpc e) None of these 23) What is the current temperature of the CBR? a) 300 K b) 0 K c) 2.7 K d) 273 K e) 0.127 K 24) Olber’s paradox claims that in a static, infinite Universe the sky at night should be a) blue b) black 0) White (1) red, as on Mars e) green ' 25) When our Universe was only 10 billion yrs old the Cosmic Horizon was a) 10 billion light yrs b) 13.7 billion light yrs c) 10 billion pc d) 5 billion light yrs e) 13 billion light yrs ...
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