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Test 2 Ver. 202 (Spring 2005)

Test 2 Ver. 202 (Spring 2005) - at F"<9 KM Version...

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Unformatted text preview: at»; F" <9 KM Version 202 February 18, 2005 TEST 2 -- PHYSICS 2022 L L 2. V :-_ V1- 4 V? Each question is worth 2 points. 1. In 35 years a star changes its position on the sky by L45”. What is its prOper motion? '- a. 2.0 arcseconds per year _ b. 1.8 arcseconds per year P 5” ‘05 0“- 561C “C. .0 arcseconds per year '. 20 arcseconds per year c. 2.6 arcseconds per year 2. Two stars have the same parallaxes but different proper motion. From this information alone, we know for certain that the two stars have different a. masses 1'). temperatures 0. distances d. radial velocities @ tangential velocities 3. A star at a distance of 46 pc will have a parallax of A J” a. 0.0156 arc minutes d 3." 4'L0 P C H b. 46 arcseconds ? @0022 arcseconds d. 0.022 arc minutes P e. 1146 degree ff 3 (9 t 02*”? m: sea. 4. A star moving directly away from the Sun at 100 kmls will have a proper motion of a. +100 k’m/s ® +100 arcseconds/year c. ”100 kmis d. -—100 arcsecondsfyear 'e. .0 arcsecondsfyear V72 300 “4g“ 5. Listed below are 5 objects and their apparent magnitudes: Sirius (in = 0), Capella (m = 1), Procyon (m = 2), Rigel (m = 0.5), and Jupiter (m = -l). Which object is the faintest? ' a. Capella ' b. Ventra— 3 is {03 e. Jupiter 6. Why are the Balmer lines of hydrogen weak in stars that are hotter than about 10,000 K? a. hot stars are made mostly of helium b. most hydrogen atoms are in the ground state in hot stars hydrogen is ionized in hot stars . most hydrogen is in molecular form in hot stars e. there are no stars hotter than 10,000 K 7. In the spectral classification of stars, strong absorption lines of which of the following atomic or molecular constituents would indicate the highest surface temperature? a. HI @1. n c. TiO (1. FeI e. Call 8. Captain Picard’s star has 3 times the radius of Captain Kirk’s star, and it is also 2 times as hot. How does the luminosity of Picard’s star compare to that of Kirk‘s star? a. 48 times as great L. z ._ 4 _ b. 1024 times as great —-—P- :(gQ-‘PJ 31E ‘ R? ‘“ ERIC: 0. 6timesasgreat L14 1 T ) T’ g. 2T @44 times as great 62)“) V' P '1‘ e. 324fimesasgreat i: =(52X&4)2144 v.4 ' 9. The coolest stars have spectral type a. H b. A c. Z @M e. O 10. Stars of different spectral types show differences in the strengths of absorption lines of various elements. These differences are due to ,af differences in the chemical composition of stars 13. differences in stellar ages ifferences in the surface temperatures of stars . differences in stellar distances e. differences in radial velocities 11. A star is observed to have lines of hydrogen and helium and no other absorption lines. The spectral type of such a star is closest to a. F8 @‘BS c. A8 d. K8 e. GS 12. Which of the following spectral classification of stars is in correct order of decreasing temperature? ' -BAFGKM b. MKGFABO c. ABFGKMO d. OBFAKGM e. KMGFABO 13. The star Canopus has an apparent magnitude of —0.7, and the star Deneb has an apparent magnitude of +1.3. The only thing that can be said with certainty about Canopus is that a. it is fainter than Deneb, as seen in our sky 2: -" O “I b. it is hotter than Deneb m1 _ c. it has a greater luminosity than Deneb m a " + L '3’ @it is brighter than Deneb, as seen in our sky # in? it: 6. it is closerthan Deneb -O._l #1.?) " 2-6 \O%(' J -. b 0.1% b = :53“ 14. The star Tau Ceti has an apparent magnitude of 3.5 and an absolute magnitude of 5.7. From this information we can say m s :3; 5 M : f5 ."i a. that Tau Ceti is a cool, red star cl @tha’t Tau Ceti is less than 10 parsecs away 35 a (:3 f‘; s ‘5 lit-3%. 11 (30) c. that Tau Ceti is exactly 10 parsecs away d. that Tau Ceti is greater than 10 parsecs away ' d 1 3 . Lo PC - e. that Tau Ceti is a hot, blue star ' - 15. The B-V index is a direct measure of what property of a star? ,a/ mass '3 surface temperature ff£1 luminosity ,df' radius lea distance from Earth 16. Which quantity CANNOT be determined or inferred by the spectral type of a star ,aflunnnosity 1 lb.” surface temperature c. absolute magnitude .- proper motion 6. radius ww- Ma telgpggi git/tat: .3 17. The spectral type of the Sun is G2 and that of the star Procyon is F5. From this information alone, we know with certainty that Procyon is a. intrinsically brighter than the Sun b. intrinsically fainter than the Sun © hotter than the Sun d. cooler than the Sun 6. both fainter and cooler than the Sun 18. Why is it that stars with low surface temperature show very weak or no hydrogen Balmer lines in absorption? a. because hydrogen atoms have no electrons in any energy levels b. because the stellar gas is so cool that there is no radiation at the Balmer wavelengths (2 . because these stars have much less hydrogen 6% because the hydrogen atoms have to be hot enough to be ionized in order to show Balmer absorption e. because hydrogen atoms have no electrons above the ground state C 19. Measurements indicate that a certain star has a very high luminosity (100,000 times that of our Sun) and yet is relatively cool (3500 K). How can this be? L at MA a. it must be very large b. there must be an error in observation, no star can have this form . c. it must be a main sequence star d. it must be quite small ' @t must be quite massive 20. A difficulty in analyzing the orbit of a visual binary is that a. the stars are very faint b. the tilt of the orbital plane is near 90 degrees c. the radii of the stars are very small the periods are very long I e. the spectrum of only one star can be seen 21. The duration of eclipses of binary stars is used to derive the star’s a. temperature b. mass @diameter d. luminosity e. distance 22. The study of binary stars allows us to derive which important stellar parameter? a. distance from the'Earth b. luminosity c. surface temperature stellar mass e. age of the star 23. Determine which type of star has the following characteristics: A star with surface temperature of 40,000 K and luminosity 10,000 times that of the Sun. a. red supergiant loo‘Dou ! @ red giant T \D‘CDQ [I ’9’.“ white dwarf L ( G 1 rd: red dwarf I I ,e.’ blue main sequence star _ . . ital-um mince 24. Determine which type of star has the followmg charactensucs: A star with surface temperature 2,000 K and luminosity 100,000 times that of the Sun. a. red dwarf b.’ blue main sequence star 0. red giant .red supergiant ,e.’ white dwarf 25. A star with a surface temperature of 5800 K and an absolute magnitude 1.5 mags smaller (in number) than the Sun’s absolute magnitude is a member of which luminosity class? a. ISupergiant b. II Bright Giant @IV Sub Giant d. HI Giant e. V Main Sequence 26. The star Mimosa is classified as B lJV, and the star Spica is classified as B1» 111, This tells us that, compared to Spica, Mimosa is a. about the same temperature, but intrinsically fainter b. about the same temperature, but intrinsically brighter ,9.” about the same intrinsic brightness, but considerably cooler ,d/about the same intrinsic brightness, but considerably hotter 3: bout the same temperature, but much larger 27. What is the physical reason for the appearance of periodic splitting and recombining of spectral lines in the spectra of binary stars? ' a. oscillations on the surfaces of the stars, leading to Doppler-shifted lines .Doppler shift of light from stars orbiting each other, and moving toward and away from Earth during this orbital motion 0. distortion of atoms on one star by the gravitational force of the other star d. the different surface temperatures of the two stars 6. Zeeman splitting of spectral lines on one star by the magnetic field of the second star 28. Stars A and B have the same surface temperature but the pressure of Star B is 1000 times greater than that of Star A. Their spectra would appear a. the same except that the absorption lines of Star A are slightly redshifted the same except that the absorption lines of Star A are much narrower _,e./ the same exactly 0. the same except that the absorption lines of Star _A are slightly blueshifted d. the same except that the absorption lines of Star A are much wider 29. What kind of stars are found scattered across the bottom left of the HR Diagram? 3. white dwarfs . b. supergiants c. giants 431: main sequence stars @Variable stars 30. Most of the naked-eye stars we see in the night sky a. are relatively nearby b. have large proper motions e. are intrinsically very luminous g; have very small masses (ES! are very similar to the Sun ...__l:_ Star Name In B—V arallax RV S e d A on Cen A +0.0 +0.60 0.815 3.676 -25 G2 V . 1 t 2 E B 0!. CMa —1.5 +0.10 0.350 1.330 -8 A1 V 2. Ma C at Ori +0.4 +1.30 0.007 0.003 +5 M2 Iab. _ 14+ 2 359, D B Gem +1.1 +0.90 0.091 0.625 +3 K0 HI \ o . qq E 1: Get +3.5 +0.72 0.289 1.920 -16 G8 V 5 .4 (a where m and B—V are in magnitudes, parallax is in arcsec, u is in arcsec/yr, and RV is in km/s. 31. Which star appears to be the faintest? 21.8er _ L2-d2"b b. StarB 4t c. StarC L .: (2.“? 32. Which star has the largest diameter? : \.. _ a. Star A \ .\: hhhhhh +... b. StarB - \ +2.23 (1. StarD \. e. Star E _ -.i n:- . I ‘. hm ..... 33. Which star is farthest from us? " o e at" Ga *3 M a. StarA 1—4: be 7— 1 ”@ch -15 , 0,4 : 2F: lugCh/bb) ' b e. StarE 0.1.”: TS: +0537... e35 36. A star in a binary system (lying in the Earth’s orbital plane) is observed to have a radial velocity of 40 km/s toward the Earth. Six months later the star’s radial velocity is 10 kaS away from us. What is the binary system’s radial velocity with respect to the Sun? a. 50 kmfs toward __ - mm __ lam-m b. 401111113 toward V2 '- 40 .__.. V12 " ‘0 Q @3 30 kmfs toward (1. 25 krnfs toward 6. 10 1011/3 toward in? ALL OF THE REMAINING QUESTIONS ARE WORTH 4 POINTS 37. The star Ross 128 has a parallax of 0.301 arcsecond, a radial velocity of 15 kmls, and a proper motion of 1.30 arcsecond per year. At what total velocity does Ross 128 travel through V s ace, relative to the Sun? H __ Wyn. .. p a. 13kmfs P =03?“ Va “”53 “4-3 b. 2 kmfs 1 c.22kmfs oraarmM'g; =Qo.“ @25 kin/s - _ WW 1 c.55kmfs V: “23,“: = gold, 93‘ '3 8. If two stars differ in magnitude by 6 magnitudes, what is the ratio of their brightness? a. 6:1 132 b 6001 “22.6103( he.) 900:1 b 1 .2503 95"7': “E; e. 1,000,000:1 ’ 39. The star Vega and the star Sirius have the same apparent visual magnitude; however, Vega is 7.8 pc away from the Earth and Sirius 2. 6 pc away. What is the luminosity of Sirius compared to Vega? ; 2 v = b a. 9times1ess Lea-TC? L32 #0“: :qL d b dv 1.7; b. 3 ti 1 . “- . c thelslzisaeess Ly (7-25) WCQO 93% d b : '2‘ La (1.3 times greater ' times greater Ls ~_ q L. v 40. Assume the mass-luminosity relation is true for all masses (L 0-: M4) and that the range of stellar masses is from 0.08 to 60 solar masses. How many times brighter is the most massive star compared to the least massive star? a. 60.08 : 1 b. 6.3x106 : 1 c. 1.3:;107 : 1 d. 15x1010 : 1 .32 x1011 : 1 41. The star 1: Arietis has an apparent magnitude of +2.7 and a distance of 47 light-years. What is its absolute ma nitude M? . I4 . 4 2 a.+2.7 g ’ 9-7‘M‘5W‘3( m b. +1.7 @1—19 d. +3.5 e. -O.6 42. Sirius is a visual binary with a period of 50 years and a semi-major axis of 24 AU. What is the total mass of this binary system? at 2 24 A0 a. 0.5 times the mass of the Sun 3 5.5 times the mass of the Sun M P 2: 0. c. 217 times the mass of the Sun 0L5 d. 4.3 times themass ofthe Sun M 7' #2: [73* 63 c. 11.0 times the mass of the Sun 9 43. In a spectroscopic binary system, Stat X has an orbital speed of 22 kmfs and Star Y has a speed of 15 kmfs. Which star is more massive, and what is the ratio of masses? a. StarX,20:1 b. StatY,10:1 MN x: MW»: e. StarX,7:1 d.StarY,1.5:1 flwfi: Q=Om5§32 -tarX,-1.5:1_ Mtr Vx 2’2 ' Constants My : DADS? Pk" o = 5.6‘7’x10'8VWm2 K4 Lsun = 3.90x1026113 1pc = 3.261)! 47 in; 'X \P‘; = 3.2mm ...
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