Test 3 Ver 203 - w i “fig-'2" .iz“. r . NAME...

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Unformatted text preview: w i “fig-'2" .iz“. r . NAME :0 eff L_—-‘=~»‘~:“--*’i_-~ MU Versron 203 March 11, 2005 TEST 3 -- PHYSICS 2022 Each question is worth 2 points. 1. The distinctive color of a reflection nebula is a. red, coming from the emission of light from hydrogen gas @ blue, caused by the scattering of light from dust grains 0. green, coming from the emission of light from helium gas (1. several specific colors, coming from fluorescence of atoms excited by ultraviolet radiation emitted by hot stars 6. light of all colors, but predominantly in the red part of the spectrum, emitted by cool stars 2. The redOminant color of an emission nebula is “(:3 red, from the Balmer H—alpha line ' b. blue, from scattering of light from hot stars by dust particles c. green-yellow, from the 530.3 nm emission line of ionized iron d. a continuum of all colors, the combined light from the stars in the nebula e. answers a, b, and c 3. The shapes of the Gas Pillars seen by the Hubble Space Telescope (slides were shown in class) were formed by a. the propagation of planetary nebulae in the region b. radiation pressure from nearby stars blowing away all material except that behind the high-density tops of the pillars c. ripples in the‘ surrounding giant molecule cloud caused by a supernovae explosion d. two colliding H II emission regions @3 rapid rotation of material, similar to eddies, in the surrounding giant__.molecular cloud 4. The source of a protostar‘s heat is ,3... radioactive decay /b.- gravitational energy released as the protostar expands 4;.- nuclear reactions converting hydrogen into helium in its core radiation pressure from nearby stars converted to kinetic energy {6‘} gravitational energy released as the star contracts 5. The lowest mass that a protostar can have and still become a star is @ slightly less than 1110 of a solar mass b. about half a solar mass ,~e. about 12'1000 of a solar mass d. 8210 of a solar mass ,e. slightly less than U100 of a solar mass 6. A protostar of about 1 solar mass is gradually contracting and quickly becoming hotter. This will cause its position in the Hertzsprung-Russell diagram to shift slowly a. upward and toward the left b. horizontally toward the right downward and toward the left d. downward and toward the right 6. upward and toward the right 7. How does the temperature of an interstellar cloud affect its ability to form stars? a. Star formation is so complicated that it is not possible to say how one quantity, such as temperature, affects it . Higher temperatures inhibit star formation Higher temperatures help star formation d. Higher temperatures allow many more stars to be fOrmed e. Star formation is independent of the temperature of the cloud 8. How long will the Sun have spent as a main sequence star when it finally begins to evolve toward the red giant phase? a. 1 billion years b. 1 million years c. 1011 years 10 million years e. 1010 years 9. The Sun has existed for a very long time without change in its 'size, appearance, or behavior. This means that it must be in hydrostatic equilibrium. Under these conditions, which two parameters must be in exact balance within the Sun? a. numbers of hydrogen and helium nuclei (1)?) inward force of gravity and outward gas pressure 6. hydrogen gas pressure and helium gas pressure d. magnetic field and force of gravity e. proton gas pressure and electron gas pressure 10. Which reaction below is the first one in the proton-proton chain? (Q) hydrogen + hydrogen 9 deuterium + electron + neutrino b. hydrogen + hydrogen 9 deuterium + electron + neutron fer“ hydrogen + hydrogen 9 helium + positron + neutrino 4%.” hydrogen + hydrogen 9 deuterium + positron + neutron ,e/ hydrogen + hydrogen 9 deuterium + positron + neutrino 11. All stars on the main sequence a. are getting smaller due to gravitational contraction b. have approximately the same age, to within a few million years generate energy by hydrogen fusion in their centers (1. spent the same amount of time as protostars e. are at a late stage of evolution after the red giant stage 12. Which of the following statements about the rate of stellar evolution is true? “at” the more massive the original star, the slower the evolution Mtars of spectral type A evolve the fastest ;_'.',QL"_I':ithe more massive the original star, the faster the evolution ed?" star mass has no bearing upon stellar evolution, since all stars evolve at the same rate, controlled by nuclear fusion we: the chemical make-up of the original nebula is the major factor in deciding the rate of evolution, whatever the mass of the star 13. Which way does a low-mass star evolve, on the HR diagram, after it has left the main sequence? ,a.» to lower luminosity and higher temperature, progressing through the main sequence toward the white dwarf stage b. to higher luminosity and higher temperature, upward along the main sequence it does not move at this time on the HR diagram and? to lower luminosity and temperature, downward along the main sequence @ to higher luminosity and lower temperature, away from the main sequence 14. The neutrino is a. another name for an electron that has a positive charge instead of a negative charge b. a heavy, uncharged nuclear particle, easily detected C. an anti-neutron an elusive, subatomic particle having little or no mass, and difficult to detect e.- an ultra-high energy photos 15. The solar neutrino experiment designed by Raymond Davis has detected a rate of solar neutrinos arriving at the Earth, which is @ about 1:3 of the predicted rate b. almost exactly equal to the predicted rate 0. almost double the predicted rate d. less than 1% of the predicted rate e. varies with the solar cycle 16. Based on your knowledge of the HR diagram, which of the following descriptions of a star cluster is astrophysical nonsense? (a/ complete main sequence (OBAFGKM) with no red giants and no white dwarfs /b./ a complete main sequence (OBAFGKM), no red giants but a large number of white dwarfs 0. complete main sequence with no 0, B, or A stars, but some red giants complete main sequence with no 0, B, or A stars, but some red giants and white dwarfs /e.’ Complete main sequence (OBAFGKM) with some red supergiants 17. The age of a star cluster can be determined by a. photometric observations of the stars that are similar to the Sun b. carrying out a number count of the stars in the cluster c. observing its position and distance in the sky with respect to the Sun d__. the turnoff point on the main sequence of the HR diagram “3 = spectroscopic observations of the stars that are similar to the Sun 18. In the HR diagram, the brightest stars in the Pleiades cluster are not on the main sequence, but away from it toward the right. Why is this? a. these stars have already become white dwarf stars, as Shown by their position b. these stars have not yet reached the main sequence, and are in the T Tauri phase 0. these blue stars have already begun to evolve toward the red supergiant phase d. these stars have already evolved through the red giant phase and have now returned to the blue giant phase on their way to the white dwarf phase @r these stars are not true members of the cluster but appear in the sky as though they I are cluster members 19. How do astronomers know that globular clusters are very old? a. there are no main sequence stars in globular clusters b. they do not contain any red giant stars their stars have a high abundance of heavy elements d. there are no massive main sequence stars in globular clusters e. they contain large numbers of gaseous supernova remnants 20. What would you expect to find in the population of stars within a globular cluster? 3. many 'red giants, white dwarfs and dim red stars, but no bright blue stars or dust and gas ,bf many young stars, protostars, and gas clouds .e/ a full range of stars from bright blue to dim red, with no bright red giant stars but significant amounts of dust and gas @ a full mixture of bright blue supergiant and red giant stars in addition to white dwarfs and dim red stars ’e’.’ mainly white dwarf stars surrounded by the remnant dust and gas from the planetary nebular stages of dying stars, but no faint red stars, red giants or bright blue stars 21. Compared to the composition of the early Sun, the composition at the core of a red giant is significantly different, with a higher fraction of He compared to H 437—“ the same, with a high fraction of H compared to He, since these stars were produced with the same initial material re? very different, with lots of H but almost no He left after thermonuclear fusion (1. very different, since nuclear fusion has transformed all the H and He into heavier ' elements '6?“ very different, with approximately equal amounts of H, He, C, and 0 22. When a star expands toward the red giant region, what is happening inside the star? a. helium is being converted into carbon in the core b. hydrogen burning is taking place in a spherical shell just outside the core; the core has not yet started thermonuclear reactions, and is still mostly hydrogen @ hydrogen burning is taking place in a spherical shell just outside the core; the core itself is almost pure helium, which has not yet started thermonuclear reactions (1. the carbon core is burning inside He and H burning shells e. helium burning is taking place in a spherical shell just outside the core; the core itself is almost pure carbon 23. If electrons are collectively compressed into a very small volume where quantum mechanical considerations become important in preventing one electron from occupying space near to a second electron (electron degeneracy), what is the result? @ the electrons generate a very large pressure to oppose further compression nuclear fusion occurs between electrons to produce energy, thereby heating the star's core half of the electrons are transformed into antimatter (positrons) which then annihilate electrons, producing a burst of energy and the explosion of the star d. the electrons fall into orbit around one another in mutual pairs which reduce the restrictedquantum space, thereby allowing further shrinkage of the star e. the large negative repulsion creates a fast expansion of the outer atmosphere of the star ' ' " 24. A degenerate electron gas lacks the safety valve of a normal gas. This is because a rise in a. pressure releases more electrons, thus increasing the pressure further (3.)“ temperature increases the pressure, creating more energy /G( temperature lowers the pressure, causing the star to contract ,dr temperature does not change the pressure, so the gas does not expand and cool e/ pressure reduces the number of electrons, causing the core to collapse 25. What is the dominant nuclear reaction during helium burning in a star? a. 4 He fusing into C b. He + H fusing into Li 3 He fusing into C d. 2 He fusing into C ' ta e. He + 2 H fusing into Be 26. Why does it require higher gas temperatures in the core of a star in order to produce nuclear fusion of helium compared to hydrogen? ' 13/ because the He nuclei need to be moving faster in order to avoid the more numerous ' and faster H nuclei b. because the He nuclei are four times as massive as H nuclei because energy generation per fusion reaction of He is much less than that in H, and u higher temperatures will lead to more frequent collisions ' d. because higher speeds are needed between two He atoms in order to overcome the shielding of the two electrons per nucleus compared to the one electron per _____—1 nucleus of H - i because higher collision Speeds are needed to overcome the extra electrostatic _" repulsion between doubly charged He nuclei 2?. The helium flash is made possible because of a. fission of helium in the core (E electron degeneracy in the core of a low—mass red giant star c. the high temperature in the helium core of a blue supergiant star weir the sudden onset of nuclear reactions at the end of the protostar stage er" the sudden release of energy in a core collapse 28. After the helium flash, the star contracts. This occurs because @ the electrons in the core became degenerate during the helium flash, reducing the volume occupied by the core _/-b. the helium flash used up all of the helium in the star's core, ending the production of energy produced by the core " ,e: the star lost about 15% of its mass as a planetary nebula d. the star‘s deep interior expands and cools during the helium flash, reducing the energy produced by the hydrogen burning shell JV energy radiated to space during the helium flash cooled the entire star, making it contract 29. An asymptotic giant branch (AGE) star is in the a.' helium core-burning and H shell-burning phase b. carbon core-burning, He shell-burning, and H shell-burning phase @ helium shell-burning and H shell—burning phase d. hydrogen shell+buming phase prior to helium ignition in the core e. pre-main-sequence phase 30. Theevent that follows the asymptotic giant branch phase is (@J the ejection of a planetary nebula " b. core collapse and a Supemovae explosion c. the helium flash and the start of helium burning in the core d. the carbon flash and the start of carbon burning in the core 6 the start of iron burning in the core 31. The physical process that provides the energy for the creation of a planetary nebula is a. when the electron-degenerate core is converted to a nondegenerate core b. transfer of hydrogen~rich material to the surface of a white dwarf from its companion in a binary star system series of thermal pulses in a helium-burning shell T a collision with another star e. core collapse and the ensuing shock wave 32. A planetary nebula is da: a disk-shaped nebula of dust and gas, around a relatively young star, from which planets will eventually form nib? the nebula caused by the supernova explosion of a massive star a contracting spherical cloud of gas surrounding a newly formed star in which planets are forming d“) an expanding gas shell surrounding a hot white dwarf V e. a contracting spherical cloud of gas surrounding a newly formed planet in which moons are forming 33. One peculiar feature of the evolution of a white dwarf star is that -=a.- they do not change their luminosity once they have become a white dwarf ab?“ its size or radius slowly increases as it cools, until it becomes a red giant star 0. it heats as it shrinks because of the release of gravitational energy, ending up as a very hot but very small star it shrinks as it cools, eventually to become a cold black hole in space its size remains constant as it cools and dies 34. There is a mass limit for a star in the white dwarf phase, the Chandrasakhar limit, beyond which the star can no longer support itself against its own weight. This mass limit, in terms of solar mass, is {5:} 1.4 E". 14 c. 0.2 d. 0.08 e. 4 35. Star A is a white dwarf of mass 0.8 times that of the Sun, and Star B is a white dwarf of mass 0.6 times that of the Sun. What can be said with certainty about these two stars? a. Star A is brighter than Star E CE.) Star A is smaller than Star B 0. Star A is hotter than Star B Np, ,, D in k _ d. StarAis older than StarB W; H iv 0 t. p M u - e. none of the above we ,g carpi-£9 36. Which force holds together the nuclei of atoms? a. gravitational bi"? electro-magnetic Kc. " strong d. intermediate e. weak 3?. Thermonuclear fusion can continue to produce "heavy" elements inside massive stars, up to a limit. The element that represents this limit is a. zinc b. uranium c. gold cl1 silicon (3.) iron 38. The process of core collapse at the end of the life of a massive star takes up a time, from the start of collapse to the attainment of nuclear density, of about a. 1/1000 second lf4 second c. a day d. a few hours e. 8 minutes 39. For a 25 solar mass star, core hydrogen burning lasts for several million years. In contrast, core silicon burning lasts for only about ' a. one year b. a day c. one month (1. one minute 600 years 40. The supernova SN 1987A differed from most other supernovae because it reached a maximum luminosity ten times that of a normal supernova .13.; it only had three times the mass of the Sun I 2&3.) the star was a blue supergiant when it blew up, rather than a red supergiant d. it declined in brightness much faster than most supernovae e. it occurred in an external galaxy (not our Milky Way Galaxy) 41. A Type II supernova is «a: the explosion of a white dwarf in a binary star system after mass has been transferred onto it from its companion «bf the explosion of a red giant star as a result of helium flash in the core c. the explosion of a massive star in a globular cluster the collapse of a blue supergiant star to form a black hole the explosion of a massive star with an Fe core 0‘0 ;:.. 42. Besides photons, the LMC 1987A supernovae was also “seen” by scientists with a. electron detectors b. neutron detectors (3.“ proton detectors 'fd. 1 neutrino detectors e. antimatter detectors 43. Which of the following is NEVER a consequence of a Type II supernova explosion? (a) the formation of a planetary nebula Jar the manufacture of the nuclei of heavy elements 0. the triggering of star formation by shock waves moving through interstellar space rd.» the condensation of matter into a solid nuclear star composed entirely of neutrons the releaSe of large amounts of neutrinos 44. Type Ia supernovae are produced by a. detonation of a CO degenerate core b. the photodjsintegration of the iron core in a massive star c. a neutron star pushed over the Chandrasekhar limit d. two merging neutron stars in a close binary system a white dwarf pushed over the Chandrasekhar limit 45. As a 2 solar mass star evolves off the Main Sequence, its temperature decreases from 9400 to 4000 K, but its luminosity increases from 10 times the sun’s luminosity to 500 times. By what factor does its radius change? Ti __ '1"; :- a'gfijr 3’3 3;“ a. 13.0 _ ' ‘ ‘“ 1,: H . b. 1.3 L l1 lUL,.Q [,2 '--- ’-’ J Lt) 3 .,.. . _/,. .- 4 @39 Lt 2- ti: £1 "= K t rig [2.2 Jen d. 1? w. .43: =7»; : he? - e. 123 p . L1 is ‘i '53; 4.3:. 2' Milli,“ 5“ 46. How much energy (in joules = kg 1112/32) is released by the conversion of 9 x 104 kg of hydrogen into helium? [Mass of a hydrogen atom = 1.673 x 10'27 kg] (Tammi: 8.1 x1021] . whit—“arr: artist-:7: ". ‘" b. 2.7x10‘é‘1 E t. . l J L EQOXIOJ [w Qyflpgwl’ax J 1 d. 5.7 X1019] e. 1.9 x 10111 47. Approximately how many years will a 0.3 solar mass star be on the main sequence if a 1.0 solar mass star stays on the main sequence for 10 x 109 years? ® 370 x 109 years I _ M I L h h i. __ :____ As? 5 x 1099years [1:35:1- ytagf 13 -' =1} ,5 " nor 10 x10 years I d. 30): 109 years i t L ,3? 0.9 x109 years The Following Question is worth 6 points. 48. Accurately draw the evolutionary path of the Sun (beginning on the Main Sequence) on the HR Diagram below. Indicate where all of the following events occur: I) planetary nebula creation AGB phase 2'] red giant phase 5") white dwarf phase 2)) thermal pulses (9“) He flash I-[R Diagram _ H. H [I 1 nm T 1...}. .f. .1 ..l__.|__l_ ‘ i I i. .!._[._I.-I_.E-{.__.: _ u .15 gm -5.o - reocc- € . r :> I' 1 . s 1 . 2.5 1 , ’- I '- l" f Ii ; E a s a a a "‘3 L! 1 :3 e. 5% 0.0 I t; > g i! g o 3 l f" 13 3 +2.59 . f a 8 § _ f! a +5.0 3-“ '\\ ' . -'—v_: 1 N—V \‘ g \. i \\ +7.5 g-w- as W ! _ z B, . Hoof—w 0.01 whuhmoanhuumiuuMuanuflumug 31 F0 K0 IL Spectra] Type 10 ...
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Test 3 Ver 203 - w i “fig-'2" .iz“. r . NAME...

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