Astronomy 10 - Fall 2006 - Filippenko - Midterm 2

Astronomy 10 - Fall 2006 - Filippenko - Midterm 2 -...

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Unformatted text preview: NOTE- , (”Tier DP QUESTIDI‘IS on your ex mu Mu}; iii—i Fiber: Be sure you answer question #1 correctly {e points of if incorrectjl [1] Dan Perley. the Head GSI for this class [Astronomy Cltl If LESS CTHU, Fall Efliltl] @ is a graduate student in astronomy at UC Berkeley. {bl lives on a moon orbiting Uranus. {c} is actually a punk rocli star in disguise. {d} can't-possibly be human, because he‘s made of pure niobium. and plutonium. {e} was brought to Earth from the Moon during the Apollo landings in the early IQTUS. {2}®ur F. The carbon, oxygen, calcium, iron, and other heavy elements in your body were created in stars and supernovae long ago. before the formation of the Solar System. [3] Which one of the following statements about black holes is FaLSE? It is impossible for light to orbit a black hole because in a vaculun, light travels only along Euclidean straight lines. E E’ ‘ lill- L5 ' 202- {h} Black holes are not totally black; they can “evaporate" by a quantum process involving the emission of particles from just outside the event horiZon. {c} it is possible. to extract energy from a rotating black hole. {d} If the Sun were to turn into a black hole having the same mass, Earthis current orbit would be unaffected. [e] Even a relatively small object, lihe Earth, could form a black hole if there were a way to compress it into a small enough vohnne. [4] Which one of the following Statements about extra—solar planet observation techniques is FALSE? {a} The majority of currently known extra-solar planets were discovered with the Doppler— shift method. @ In the Dopple1-_sl1ilt method, the changing radial velocity oifmtlgg Exit—KS tar; plafit' is measured from a series of spectra of the extra—solar planet itself. P mfl;:,.-g +52: 51.1,. dill; *1. {c} The Doppler—shift method gives us only the minimum possible mass of an eat-farsolar planet, unless we have additional information about the inclination of the planet‘s orbit. {cl} The transit method requires the extras-solar planet‘s orbit to be aligned closely with our line of sight. to] The transit method can sometimes give us information about the composition of an extra- solar planet’s atmosphere. {5} Which one of the following statements about collisions with Earth is TRUE? If the comet that collided with Jupiter in 1994 had instead collided with Earth. the impact would have been very destructive. [bl Small meteoroids that enter Earth’s atmosphere many times a day, releasing heat as they disintegrate. contribute 'simdflcantly to the current episode of global warming. to] The impact that likely created the Moon also destroyed much of the life that existed on Earth at that time, including the dinosaurs. [d] The Cretaceouszcrtiai-y extinction following a comet impact 65 million years ago was caused by poisonous iridium that the explosion distributed into Earth's atmoaphere; [e] Even if we discovered all the near-Earth objects in the Solar System, we would have no way of predicting when one might collide with the Earth. {6} Which one of the following statements about gamma—ray bursts is FALSE? {a} Most of them are probably associated with the JLirzrruzlation of a black hole. {b} Most of them occur in distant galaxies. C3“ 2” The explosions emit about the same amount of energy in all directions. { ]I The gamma-ray emission from a gamma—ray burst cannot be detected from the ground. {e} Some gamma—ray bursts appear to be associated with supernovae. {T}@or F. The center of mass of a binary system might actually lie inside one of the taro bodies. as. film" :1 c, - Isl find-I'd- Plfithfir-l {8] Star Amber’s spectrum peaks at 25th] Angstroms, while Star Fosteris spectrum peaks at Elltiil Angstroms. The luminosity of Star Amber is 134 times that of Star Foster. Therefore. the radius of Star Amber is T A _ : 7E if {a} half that of Star Foster. —fi- = —'E" Slfltfi AMT '- ' ' ll'Jl' the same as that of Star Foster. TF AH Eli) twice that of Star Foster. 53? '1]; SW _ 1 1 to} sixteen times that of Star Foster. TF 1 'i' E11) '7: (hi-Y Ti)? :(6’1‘ "L a» R. ...»._ L/Lr 12F LF 7:4 it Ll {d} four times that of Star Foster. '1 " " {Ell} T 01-6]? Pulsars are thought to be neutron stars that periodically grow bigger and smaller i: wi time. thereby getting brighter and fainter with the same period. Pfi _,, 2 E 'I-fi. 1- CS -1Ci5.' pulfiil‘i-‘j due to mtoiicfi . {113} Most of the Sun‘s energy that is radiated into space is released as thermal {nearly black—body} T.risible and inirared radiation from the photosphcre. {h} T.risible and ultraviolet emission-line radiation from the chromosphere. 4... Hanse- uassty n. has to} l‘l—ralfs from the corona. {-— Fm‘l'm “n “‘1'” 3" mil-“it {d} gamma rays from nuclear fusion in the core. rare “1'5 Abflt'il “PM" its Euthan- to} radio Wares from an intelligent civilisation hiding under snnspots. [11] 1il'ilhich one of the following statements is FALSE? {a} a random star selected [row the main sequence is more likely to be a red dwarf than any other kind of star. [b] If we observe two stars of spectral type K, it is possible for one to be a. suporgiant and one to be a. riwart'+ to} A star cluster whose main sequence contains stars only of spectral type A.F,G,K.M,L is likely to be younger than a. star cluster whog main sequence contains stars only of spectral type G,K.M1L+ {15415154. % {d} A. star that is 10.0130 times as luminous as the Sun can still fail on the main sequence. The main sequence traces the typical life cycle of an individual star as the star mores trons upper-left to lower—right on a temperature-luminosity diagram. {12} Most Earth—orbiting satellites rely on solar 1'Jowet' collected by solar panels attached to the satellites. If one of these satellites were sent to Saturn {about 1!] All. from the Sun}, how much larger or smaller would the solar panels have the made to supply the same amount of power to the satellite? .... f I. {a} ltltl times smaller. ‘3 " mL x ‘55 ill-la 5% WI 6;) :- .1- {b} 1t]I times smaller. c 1t]I times larger. ‘35 L‘rfifi firm 51“”le ) E ELM-I “ch“ QM firfii. ltlil times larger. 51.: 3 {e} The same size. because the amount of energy collected by a solar panel is independent of distance from the Sun. [13]: Which one of the following statements about star and planet formation is FALSE? (a) A. pre—main—sequence star radiates energy supplied by gravitational contraction. {I1} 11 prermain-sequcnee star becomes a true star when nuclear fusion of hydrogen nuclei into helium nuclei begins. {c} During their gravitational collapse. giant clouds of gas and dust liragment into smaller collapsing units, generally giving rise to star clusters. (IE-I) The planets that tend to form around young stars 1: o-pie from clouds of gas. known as ' p auetary nebulae," sturounding these stars. ESS— I'J’t F'W" ”‘1' "Eb“; “ ‘ filflh‘i sneer-1 “'1 L” “l” [e] Hydrostatic equilibrium. is achieved in a star when the inward Ji'orce of gravity is balanced by the outward pressure of the hot gases. [14}®or F. Brown dwarfs are not complete failules as stars: they fuse deuteriuur a. heavy form of hydrogen. for a short time C5” WE. [15} Which one of the following statements about parallax is TRUE? {a} rlhc distance of a star 1s given by the simple formula. d— — 1f ftp where cElia [peasured in light— —ycars and p is the parallax angle. measured in degrees. twine":“Eiff:@fi_‘;~1::?jiulmi lb] The distance to the Sun was first determined using the measuriitl parallax of the 51111 [c] if you want to measure the parallax of a nea1 by star accmately you should pe1 {cum all of your measurements on the same calendar day of the year. it"s"; lfl‘? '5 WDHJ’F” J:!.1"-‘¢'*LF"l" LS— 4'57 15111 observel on Merculy would measure a smaller parallax relative to an observer on Earth for the same star. 5"“ ”'9" 5'55" “E 3 Sr”"’?—" mrellflx is» like” {a} The parallax of a star refers to the amount by which the wavelengths change as it 1s gravitationally tugged by an orbiting planet. / Her- {15} A star leaves the main sequence when {a} nuclear burning has converted the core to carbon and oxygen. _ b: {b} helium begins to undergo nuclear burning in the core. “:3 {L l the helium in the core is used up. {d} hydrogen begins to undergo nuclear burning in the core. (ED the hydrogen in the core is used up. 'igs spectral lines It i 7} T or ® Degenelate matter. like that in a white dwalf or a. neutron star. is not electrically neural. and the strong electric repulsion of the particles prevefigsfi glavitational roll tattle degeneracy Freud”? IS quantum H'Ul-I- m‘c-qlr and Hal-he!“ ‘b aha-13a. [18} Which one of the following statements about the Sun is FALSE? {a} The magnetic field of Earth protects us how the full force of the solar wind. a stream of electrons and positive ions coming from the Sun- @ By watching long-lived suns ots1 we can measure the 11115 srotation period to be about 11 years. entails-1P1 per; 15 "" l Month. 3‘1“"- flilrl'f CT'JE ' M“ ‘5'”an {c} Sunspots are cooler than surrounding regions of the photosphere because the strong magnetic fields associated with snnspots inhibit the rise of hotter gas from the Sun's interior. {d} H you were to take a sunspot and place it in a. dark area of sky, it would look bright relative to the background sky. {e} Corona] mass- ejections, solar flares. and prondnences tend to he more numerous and energetic near those of sunspot Inazinlunl than sunspot minimum. {19} T [email protected] The Schwarcschiid radius of a black hole a proportional to the square .s the black hole:s mass: thus the Schwarsschild radius of a EGG—solar—Inass black hole is 1E") times larger than that of a 2G-solar—mass black hole. *1 2_ R5 = 2":— s‘ 1‘1 not M f '1. C.- {20] Which one of the following features is NOT commonly seen in the extra—solar planet systems astronomers have detected so far? {a} Very large planets1 more massive than Jupiter. fl‘lqo {b} Planets extremely ctose to the stars they orbit, closer than Mercury is to the Sun. [e] Planets with very eccentric orbits, more eccentric than that of Pluto. {d} Multi- planet systems. with several planets orbiting the same star. :5. .45 @ Small planets, with masses similar to that of the Earth. lee—Ma [21] Which one of the following statements about Type 11 supernovae {associated with the deaths of InaSsive stars] is FALSE? {a} Most occur in, or near. regions of star formation. flij The amount of time between the formation of a star and its explosion in a. Type II supernova can be as long as 10 billion years. 1"- mfles-aws stars are Very start-brad, {c} They can produce elements heavier than iron. HOD m'll'on Vflflfl {d} Supernova 1987A was an example of a Type II supernova. {e} Most of their energy is emitted in the form of ghostly particles called neutrinos. [22} (15)::- F. in nuclear fusion, the mass of the final product is less than the mass of the initial react-ants: the mass difference {m} is converted to energy according to Einstein‘s famous equation. E = me2. [23} How do astronomers know that the so-called “stellar—mass black holes," with masaes typically about It] times that of the Sun, are probably black holes rather than neutron stars? in) These objects are optically quite dark, but neutron stars are extremely bright at optical wavelengths. [b]: Spectra of these objects show that there” are no neutrons in them. {c} Powerful Hawking radiation is detected by gamma-ray telescopes pointed at these objects. {:1} These objects are observed to be sucking in matter at a tremendous rate from the parts of the Galaxy nearest to them. ‘3 Neutron degeneracy pressure cannot support a. lfl—solar-mass object. (5—100 .. I' _ ‘1 l i' m m. [24‘] Which one of the following statements is FALSE? meta: - Sawf- filial fur Egmflfdre.d (it) A meteor’s tail always points away from the Sun. H ‘i Laud- 1.91;: .. imp 5 _,_.—.- [bl Amino acids, the precursors to life. have been found in some meteorites. poll‘fi WI“.- ”um 5”" {c} “Shooting stars” are meteoroids that burn due to friction as they pass through Earth's atmosphere. [d]: A given meteor shower occurs at about the same time each year. to} Some meteorites found on Earth came from the Moon. {‘25} Which one of the following could NOT be a white dwarf right now, or at the specified time? {a} A star that has a luminosity of about 1 ,r' lflflfl that of the Sun and a temperature of 113.0130 K {h} The Sun a about 1c billion years. _ ‘ . _ _ i! . g A star having a mass 'of 3 solar masses. LE lBB ' Lh‘mtir'MLhm—l 11+ It" L4 me i A star having a mass of 1 solar mass and a radius comparable to that of the Earth. {e} A star in a binary system that becomes a nova, suddenly brightening bit-‘3‘ large amount. "‘- rlai't-i more is. 4. street fi-u-n LtL-‘l' mtnltt End of Examination ta} fype Ia Softer-flail?! . ...
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