Visions of the Universe
Visions of the Universe ISP 205
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Ms. Adrian Buckridge
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Popular in Integrative Studies Physical
This 67 page Class Notes was uploaded by Ms. Mckenzie Labadie on Saturday September 19, 2015. The Class Notes belongs to ISP 205 at Michigan State University taught by Jack Baldwin in Fall. Since its upload, it has received 380 views. For similar materials see /class/207720/isp-205-michigan-state-university in Integrative Studies Physical at Michigan State University.
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Date Created: 09/19/15
Some Basic Facts to Know What IS the age ofthe solar system7 How do we lmowv unnatlstneAgeoftneunwecsev How dowelmow7 mass othe Sum How do we know the masses oftheplanets7 Motions of Objects Kepler s Laws 1 Each planet moves around orblt In elllpse Wltn sun at one focus 2 The stmlglnt llnejolmng the planet and the sun sweeps out equal areas of space In equal amounts oftlme 3 p2 3 Newton 5 Laws of Motlon l Object smamentum doesnot changeunless acted on by a force 2 F ma 3 Conservatlon oftotal momentum ofsystern Actlon rReacLlon or Newton svaslon P2a3mm2 Gmm2 Gravlmtlonal force 2 Angular momentum Both amount amp dlrectlon arecamerved Genaal Relath lty Objects move In stmlgnt llnes through curved space tlme You cannot tell we dffereme between freefdl andle afgmwty The Motions of the Planets Copernicus 1543 Simpler made Newton 5 laws Sp ecial amp Gener a Relativity Much more accurate yet Accurate ln meme sltuatlons Genaal descnptlon ofeva ythlng Proofs of General Relativity Rapid precession of Mercury s orbit Phenomenon known before GR offered the explanation Bending of light rays passing near Sun First measured in 1919 Time dilation in gravitational elds Measured using real clocks on Earth Gravitational redshift in strong gravitational elds Observed in spectra ofwhite dwarfs 1 t e ectromagnetlc wave H m Htl gt w in 39 t t t t um 4t gt equenvglmjnrzte at which crests pass a stationary observer f velocitydistance cA cyclessecond Energy of each photon E hf hcA h Planck s constant Inverse square laW F L 4an Black Bodies 39 Wien Displacement Law 1W 3x106 T 1 Total energy emitted per unit surface area E c T4 SteffanBoltzmann Law WZV mg h 9 Emission amp Absorption Lines Bohr Atom Electrons can onlybe in orbits at certain special molii Only one electron canbe in a given orbit at one time ectron s energy stays constant while it is in orbit Each Bohr orbit has its own distinct energy For electron to move from inner orbit to one further out it must gair exactly the energy ditrerence between the orbits Absorb photon with correct energy Electron falling to lower level can emit photon with energy e exact energy difference between levels 63 6n 06 r900 i o I lt7 9 Source of Observer incoming igt sees absorption photons lines Lots orphotons emitted in lots of random direct ons Overview of Solar System The solar system is a disk Rotation of sun orbits of planes all in same direction Most planets rotate in this same mighiinhiiiu sens nus Uranus Pluto are 139 exceptions m z 39 Angular momentum ofpresolar gas 5 t E E5 oud I Terrestrial vs Giant lanets y i m i u forum 4 Q In the Solar Nebula while theplanets were Presence or ice High vs low density more materialror core Rocks vs muggy gas could gravimtiunally attract large masses of hydrngm amp helium gas Composition eavy elemenm Vs primarily e Difference due to distance from Sun Terrestrial Planets rth Differentiated Ironnickel core Mantle of lighter rock Thin crust on top Plate Tectonics Plates formed at ri s usually in ocean Drift amp collide 7 Subduction Evolution of atmosphere Thick C02 9 life 9 N2 02 Current global warming 7 Greenhouse effect 7 Manmade COZ Moon Impact craters as clocks Old highlands 4144 billion yrs Heavily cratered Maria 33 38 billion yrs Fewer craters Rocks from each brought back by Apollo astronauts Age dating Chemical composition Tidally locked to Earth Formation of Moon 4 theories Giant Impact is current favorite Mercu Closest to Sun eccentric orbit Airless heavily cratered Hot but slightly colder than Hell e dense mostly ironnickel core Geologically dead probably But rupes 9 shrinkage at early time Rotates in 23 of its orbital period Tidal locking with a twist Terrestrial Planets continued Venus Differentiated like Earth But no tectonic plates Surface mostly studied by radar Large volcanoes Continents pushed up by tectonic ows in man e Recent lava ows constant resurfacing Crater density 9 very young surface 7 only 800 million yrs old Thick COZ atmosphere Result of runaway greenhouse e ect Keeps surface very hot 900E 7 Lead brimstone sulfer are molten Retrograde rotation Probably due to giant impact Ma TS 50 smaller diameter than Earth 15 times further from Sun Many visits by spacecra Small metal core but much activity in mantle Gigantic volcanoes 50 highland continents Tharsis bulge Cracked open to form Valles annens 50 lowlying lava plains 4 billion yrs old crater counts Atmosphere C02 like Venus but very thin Runaway refrigerator effect Atmosphere gradually escaped Could not retain heat Water froze out 7 even less heat retained Life Viking landers found no sign In meteorites from Mars Very questiona e The Giant Planets Jupiter Saturn Uranus Neptune 14300 x more massive than Earth Massive H He atmospheres B far the most abundant elements in the solar system On top of rockice core with 1015 x mass of Earth Lots of weather on Jupiter amp Saturn Ammonia NH3 clouds Strong winds at different latitudes differential rotation Cyclonic storms Juphlr 59 sc 1 F Great Red Spot a 7 2 x size of Earth 8 7 400 yrs so far Investigated by Galileo probe Uunul ranus Neptune have methane re ective layers bluegreen color Neptune has high altitude clouds of methane ice crys al Radius 0000 Moons Jupiter s Gal Jupiter ilean moons as we get closer to Jupit Callisto 7 ice geologically dead Ganymede 7ice but geologically active Europa 7 rock but covered by ice pack over liquid water Triton lo 7 rock extreme volcanic activity 39 Neptune s largest moon Gradient of properti ue to 39 RSWOgTade orbit increased tidal effects amp heating 75 rock 25 ice from Jupiter Very thin N2 atmosphere Jupiter s 24 other moons are much Pluto amp Charon smaller Saturn 31 known moons No spacecra visits so little is known largest is Titan gl gnprobably quite Similar to 39 N atmosphere Charon is half as big as Pluto 39 Slg llalnar to Bath 5 but Very 001d Debate about whether Pluto e e 008 39 should be called a planet Very low ma Eccentric tilted orbit Similar to some comets CassiniHuygens probe to land in 2004 AsterOlds Small rocky bodies in orbit about sun Rings from formation of Solar Ail 4 glam gaffe have rigs Most but not all in asteroid belt Rings form inside Roche limit 5 E mfg m i 2 3 ytoaml vflfi ifvil ix Meteomes enods Asteroids thathit Earth and don tbum p 39 up in atmosphere Analyzing them Age of solar system 45 billion yrs 39 Initial cherriical composition of solar system This tears bodies apart unless gravity internal tensile strength can hold them together For orbits inside Roche limit prospective moons aretom apart Comets Jupiter Uranus Neptune have Very Mostly ice thin rings Saturn has much larger rings Some on highly eccentric orbits 39 Spectacular tails when close to Sun Meltedice39 39 Rings made ofgravel and small bits of ice Most come from Oort Comet Cloud at edge of solar system Some from Kuiper Belt just beyond Pluto What Powers the Sun Need to provide 4x1026 watm lt 2x1033 grams mass of Sun gt 45 billion years age of Earth Nuclear fusion reactions 4 x H gt 4He neutrinos energy Helium AHe Hydrogen H l Computing the structure of the sun See 153 For every point in the Sun we want to compute temperature Ifquot H v 39 Pressure 4H composilion density L 6 1 composition fHe M D energy generation mi energy transport mechanism quot7 densr y We can write 4 equations expressing the following ideas The Sun is a gas 1 The sun is neither M H 39 contracting nor temperature expanding The sun is neither heating up nor v cooling down pressure Specify method of I energy transfer 7 r 51 quoteranulauon m Mini 0 TVS raglan radilTs Photosphere Deepest layer from which light directly escapes into space Low density and pressure but hot 58000 K Granules Tops of convection currents Chromosphere Transparent gas layer above photosphere Corona T gt 1000000O K Very low density 103910 bar Heated by magnetic energy Magnetic Fields Control Much of Sun s Surface Activity Sunspots Cooler regions where lines of force enterleave surface Solar Wind Charged particles with greater than escape velocity escaping through holes in magnetic eld Prominences Charged particles following magnetic lines of force Flares Magnetic field lines short out Huge burst of charged particles 1122 yr Solar cycle Due to winding up of Sun s magnetic eld Reaction Min Temp 41H 9 4He 107 K 3 4He 912C 2X108 12C4He9 WONeNa Mg 8x108 Ne 9 OMg 15109 0 Mg 5 2x109 Si 9Fe peak 3x109 Evolution through nucl burning ear Mm gt 3M Nuclear buming allthe Mimual lt 3M0 Nuclear buming shuts E off after He ash Nuclear burning in stars Here Evolution through clear buming nu Mi gt 3M Nuclear burning an the way m iron Mi lt3M Nuclear burning shuts off after He Binding Energy per Nucleon v a no so m m Atomic Number How do stars get from here to there Mass loss 39 Supemovae m m m There Final state Mmgt3Mo Black hole 14ltM llt3M Neutron star MMlt 14M The Chemical Enrichment of the Galaxy All elements heavier than Hydrogen Helium amp Lithium formed through progression of nuclear reactions in stars White dwarf c Interstellar Gas Stars 3 i as a Abundance l h iquot w i a t quotv e lroiri Kw AWW i injor icqliuiniinerz Star Formation Stars form in dense gas clouds molecular clouds Shielded from UV radiation by dust atoms are combined into molecules 2 nd also H0 N39Hj CO plus much more complex molecules Star formation disks around stars annels out ows into doublelobed patterns Planes form in these disks What types of planets are out there parent star Burwlyidug12mtplmkmatkn wn IAU 7 spiraling into the star as a result af iction Also 3 Earthsized planets circling pulsars inhospitable environment These planets are thought to have formed a zr the supernova Future spacebased searches u M4 Galaxies Composed of 100 billion stars or more Main types are Ellipticals Spirals Regular spirals Barred spirals 5 Our galaxy the Milky Way is a spiral With a weak bar Spiral arms Density waves Vs winding up due to differential rotation Site of increased gas density star formation Theories of galaxy formation topdown vs bottomup Mass of galaxies dominated by Dark Matter Detected by studying motions of stars around galactic centers Quasars amp Active Galaxies 39 Large redshift 9 large distance F L47rd2 47rd2 F L 39 Measured ux distance 9 huge luminosity Up to 1000 x luminosity ofan entire galaxy ofstars 39 Rapid ux variability 9 small volume Some luminous quasars vary in few day no 4 9 same size as solar system Black Hole t W Result of extremely strong gravitational field Schwarzschild radius 39 Energy Source Gas stars fall into 102 MG black hole Gravitational potential energy thermal energy light 39 R 2GMc2 The Black Hole at the the Galactic Center P2 M1 M2 a3 1 Velocities of stars in very center quot 9 black hole at position of Sagittarius Aquot oquot 106 MO 015quot Infrared observations over 6 years show proper motion mi Possible Geometries of the Universe If 27 4 1117 Posnive gage th Curvature urva we 395 5 5 53v a 35933 6 by Flat qu x g g g a zero curvature 8 3 An Expanding Evolving Universe Hubble s Law Galaxies all recede from us Velocity proportional to distance r d u We are unlikely to be at exact center Velocity gt Scale ofthe whole universe is expanding Scallo urwcrsa Firtnm The History of the Unive E E i g E 1 mm 300000 Years 1 mum Val Age ni m minIsa Nucleosynthesis axy ofH He Li Foma m Manm Decoupling ofCMIB Hot gt Cool High density gt Low density How do we know the universe is expanding from a very much smaller size Hubble s Law Cosmic Microwave Background CMB Telescopes 5 Galileo s telescopes N1 in diameter X 2430 long 0 Magnify images 9 see details 0 Gather light over large surface area 9 see fainter objects F mmwm q Using a lens refractor Fig52 Using amirmr relector Fig 53 Some large groundbased optical telescopes Twin Keck 10m I h I Lick36 Rel ractor 7 Iquot A 1888 Mt Palomar 200quot Re ector 194s Lightgathering power 0c mirror area 0c mirror diameter2 Technological advances Lenses 9 mirrors 0 Thick mirrors 9 thin mirrors Europe Very Large passive 9 active support Telescope 0 Now working on designs for Four smtelescopes 30m diameter telescopes Mirror for Gemini 8m Telescope SOAR MSU s New 4m Telescope Superb image quality Hi ghly competitive Superb site in Chile gt for opticalinfrared observati ans Start An International Partnership MSU University of North 2 a g air 3 n o a Cerro Pachiin Chile SOAR mirror casting Coming Glass Works 7 quot r 339 w Blank Ready for R2 Grind HHandlIng Fur Plano Grind Just nished polishing the mirror y BFGoodrich inDanbury Cl39 Radio telescopes wavelength Angular resolution mnrordiarneter Radio wavelengths are large 9 need large mirror diameter to see small angle details Arecibo Puerto Rico 1000 ll diameter but same angular resolution as 001 It optical telescope Radio galaxy Cygnus A Telescopes in Space Atmosphere block gm mu 3 Atmosphere blocks light at many wavelengths Atmospheric turbulence smears out images 24m diameter mirror Ultraviolet optical infrared quotW Above most of Earth s atmosphere High angular resolution A Light not blocked in ultraviolet or infrared 39 Low earth orbit 600 km 370 mile altitude WW 39 95 min orbits Earth blocks View half of each orbit But can be reached by shuttle to install new instruments Launched in 1990 To be replaced by JWST in 2008 Exploring the Solar System Information explosion in N 1970 s due to space ight Great source of Solar System info Nine Planets website wwwseds0rgbillatnp Partial list of missions Moon 1 Luna3 1959 2 Ranger 196465 Luna 9 lander 1966 4 Apollo moonwalks 19681972 Venus Mariner 2 1962 6 Venera 7 lander 1970 7 Venera1516 orbiters 1983 8 Magellan orbiter 199193 Mars 9 Mariner 4 1964 10 Mariner 9 orbiter 1971 11 Viking 12 landers 197680 12 Path nder rover 1997 Outer planets 13 Pioneer 10 1973 14 Pioneer 11 1974 15 Voyager 1 19791980 16 Voyager 2 19791989 17 Galileo orbiterprobe 1995 18 Cassini orbiterprobe 20022004 Contents of Solar System Sun 99 9 planets Moons Asteroids rocky miniplanets up to a few 10 s ofkm dia mostly in orbits beWteen Mars and Jupiter Comets icy spend most of time at fringes of Solar System Dust gt meteorites Mercury Venus Earth Mars The nine planets Jupiter Saturn Uranus Neptune Pluto The orbits of the planets Planets all go around Sun in same direction Except for Plutothey are in nearly circular orbits in thin plane These Views look down on that plane at 450 angle The rotation of the planets same sense as orbital motion except Venus retrograde very slowly Uranus Pluto tipped on side 39 Two distinct types of planets Terrestial planets small rocky made of heavy elements silicon oxygen iron etc Giant Jovian planets large primarily gas ice amp liquid hydrogen amp helium and then there s Pluto Planet Density E glcmquot3 5 5 E 4 Mercury 54 g 3 Venus 53 E Earth 5 5 E Z ars 39 3 l Jupiter 13 D L Saturn 07 g g E g g g g 2 g Uranus 12 g E IE E g 5 E lt3 E Neptune 16 D E D g Pluto 2 1 Terrest1al vs G1ant Slze amp Earth Mars Pluto in E gar 0gt Juplter Saturn Uranus eptune Differentiation Heavy stuff sinks to center of planets Giant planets total mass density small solid cores 10 mass of Earth Terrestrial planets cores contain iron nickel etc lighter silicates make up crust This separation must have occurred when planets were hot amp liquid Moons amp Rings Planet Known Moons Rings Mercury 0 Venus 0 Earth 1 Mars 2 Jupiter 16 Yes Saturn 19 Yes Uranus 18 Yes Neptune 8 Yes Pluto Some planets and moons shown in correct relative sizes Earth Venus Mars Planets orbit around Sun Moons orbit around planets Ganymede Titan Mercury Callisto 10 Moon Europa Triton Pluto A look back at the Solar System um us mu m u The View back from Voyager 1 on its way out of the Solar System Mosaic of images taken at a distance of 40 au 4 billion miles from the Sun The Sun is blocked out to make the planets visible The points marked J E V S U and N are at the actual locations of the planets The 39V 39 little boxes show blowups of each planet image the planets are all just little dots Note how the planets are in a plane The Earth as a Planet Material from Chapter 7 Whole chapter Chapter 3 fast skim over sect 32 35 36 37 box on page 73 Age dating from radioactive rocks 63 Radioactive decay quot nuclei quot 39 Example Uranium238 Lead206 4 x Helium4 39 HalfIi e 1 Time for 12 of g radioactive nuclei g to decay g 8 S E Nurnba ofhalfrlives Fig 611 Minerals form with radioactive elements decays produce daughter nuclei that shouldn t be in pure mineral Ratio in 39 39 39 wa Junneu This shows age of Earth Moon 45 billion years The Earth s Atmosphere lono anm Weighs 136 pounds per square inc 39 10396 of total mass of Earth 78 nitrogen 21 oxygen argon H20 COZ etc E Ozone 03 is critical for life 2 loc s Sun s ultraviolet radiation E Ozone hole over Antarctica where ozone destroyed by man made pollutants Where did it come from Formed with rest ofEarth Released from interior 7 Y meim A Dumped onto us by comets Fig 71l Mnminhmu snww Life 74 Started in CO2 atmosphere roughly 4 billion yrs ago Life initially only in sea converted CO2 to oxygen through photosynthesis The released oxygen was swallowed up in interactions with surface material until N 2 billion yrs ago A er 2 billion yrs ago oxygen able to build up in atmosphere geological activity buried much of the free carbon Atmosphere then converted to today s mix 78 nitrogen 21 oxygen 1 everything else Free oxygen ozone protection from ultraviolet light land animals Seasons 32 Heating of Earth s surface determined by ux of sunlight 39 39 39 y quill lucm pcl cwuu Think ofincoming raindrops Earth s orbit nearly round not a factor But tilt ofEarth s axis conservation of angular momentum gt much higher ux in one half ofyear than in other Global Warming Greenhouse Effect Incoming sunlight passes through atmosphere Absorbed by ground Reemitted as infrared radiation 39 v l W 5 CO2 gas causes atmosphere to be opaque to infrared ligh Fig 714 Infrared light is trapped so heats surface The Problem Human activity causing huge rise in C02 other gases So temperature is going up What will the consequences be Lots of scientific debate about the details 330 Is the CO2 increase really causmg m 310 g the temperature increase 5 m i Manmade greenhouse effect is clearly i driving up the temperatures A m 0 But other gasses have bigger effect per 35 39 39 39 39I molecule than does C02 mo mo mm mm MO 2000 Yr 0 H OW hot will it get CO2 concentration from Antarctic ice cores Predictions uncertain very complicated interactions between atmosphere and ground 3quot C 50 F increase by 2030 is typical prediction men lane was men me was me 2 on For more info Hemispheric and mean global WWWemsPSUedUlnfOGXPIOTC temperature trends 1854 to the present GlobalWarming html The Interior of the Earth Crust N6 km thick under oceans 2070 km thick under continents Rocks composed of silicon oxygen etc 03 of mass Mantle Slowly owing semisolid rock Core 7000 km diameter Metallic iron nickel sulfur Outer core is liquid Inner core probably solid Plate Tectonics Crust split into huge plates drifting around on top of the man e Driven by convection same as bubbles in boiling water M Plates pushed apart in ml WmME ri zones 39mid ocean 39also Red Sea Great Ri Valley Plates bash together in subduction zones eg Rim ofFire around Paci c Oc ean Fig 77 Also zult zones where one plate slides alongside another Geological Activity on Earth Plate collisions big time wrinkling mountain building e g Himalayas Andes Volcanoes Magma molten rock forcedupwards from mantle Along midocean ridges Ii zones 1 0mm mm Around subduction zones Rim of Fire gt mm mm Hawaiian Island chain C tdr39ft ms 1 s past hot Spot as my DI mancocw m M 39 Unusu mm quotEvMm Volga mm 13 Mn k 055 nmmmm mm m w 3 EHSWWzifgfvg m39a gm z IHotSpot W m Geological Activity elsewhere in the Solar System 63 Buckling and twisting of crust Mountain building Volc anoes Caused by hot interiors Presently occurring on 39 Earth Venus Mars Several moons of the giant planets Formerly occurred on Moon Mercury lava ows How can we tell when this happened Impact Craters J x t w 1 Cram rnrmau39nn ram W Time befnre present billions nfyears Earth moon or other large body runs into lots of small stuff Requires intersecting orbits between the two bodies Usedto be lots more small bodies on intersecting orbits We have already smashed into most of them Callisto a moon of Jupiter Chicxulub Crater Yucatan Gravity gradient map 170 km 39ameter 65x106 years old Wiped out dinosaurs Mass extinctions Closest impact crater Calvin MI 85 km dia 450x106 years old NO PICTURE AVAILABLE Barringer Meteor Crater Arizona 12 km diameter 49000 years old Made by 100000 ton ironnickel meteorite With diameter ofN50 meters are New sources of zel Fission vs Fusion Iron Fe is the most stable nucleus Fission Fusion pig iuA 1 25 J Heavy nueieus e g Uranium Ligntnueiei e g Hydrogen breaks up into iignternueiei eornbine to form heavier nucleus Where We came from H He Li are only elements formed in initial formation ofuniverse otons neutrons an simplest stable combinations ofpr d electrons it view iiE E 2 Me or stars Following He c burning core never gets hot enough for furthex reactions Mm Temp 4 H He in K H xiiix He 9160 Ne Na Mg airinx Mg 1 siriny Fusion in stars increasingly ziriny more complicated but more si Fepeak airiuv stable nuclei Penooie Table is in order ofcomplexity Up until iron Fe energy neruueienn 9 helium uranium Ftsston Mnsst O Fingl7 u m in no so Luminosity e The future of the Sun Emir moi mtgquot m Lowyyrng lava plains average of 3 miles lwerthan continents Same age as lunar maria r u mum yrs era Tharsls bulge uplifted cantment rnrles high nasmgevormoe 9 miles monomer high Valles Marinen s 3000 miles long 39 would stretch clear across US Huge tectonic crack in Tharsis bulge 39 576 miles 3mm mile diameter wuuld cuveer luwerpenmnsula largest muuntam m Sn ar ys em mu xvulume orMaona Lua Lessthan inn millrun yrs old impact crater cuunts su Mars is 51m geulugicallyadwe Lime air Very co d almost no liquid water Low atmospheric press The Martian Atmosphere ore Water goes straightfrorn me to vapor No Greenhouse effect because there is so little atmosphere orrrvurroerrvmg H10 ice letl rrr summer miles rm Southern Cap AlwavS beluwl quot K 7279 so Coztmzen allvear Unknnwr mrxntcozand Hp ice Northern Cap Climate change Used to be lots of running water 39 Runoff channels From rarnsrorrns billions ofyears ago if Fig 722 Climate change Loss of almosphere Law eseape veluclty Plus eerre serlidined magnetlcfleld Went ayia Fig 7 27 gas stripped err by solarwrnd pariieles Luvv air pressure Water freezeeuut cannut retaln heat 4 m Recently made runoff channels s en byMals Gluba Sulveyul bullhese ieaidres are yery rare Subsurface Water Mars Odyssey flrldlrlg luts err Waterlus i beluvv sdnaee as u h Life on Mars Percival Lowell Canals 1906 lots of staring through a telescope What did he really see Life on Mars ea d an MarsA 5 billlun yrs agu Eieded bymeleullmpacl l5 rnillipn yrs agu Eyenidallyeapidred by Earin ll Viking landers analyzed SEIll samples Extremely sensiiiye searen we signs pi lire adi iney unly rneasdred in 2 lucalluns Claims of organic com ounds possible micro fossil Probably Wrong Cunsiderable skeptlclsm arnung many SElErltlsts The Mars Rovers Searching for former lakes and oceans n lday Cally earneras speeirprneiers alphar pariiele deiedpr gllndel geulugy Meridiani Plain Hemame aren made ms depesis Famlevhmsprlnm Gusey Craier rprrnerlakev l rnile Possible ending 1 a white dwarf Electron degeneracy pressure to suppon star up to 1 4 Me Possible ending 2 a neutron star If degenemte electron pressure cannot support the star e p n neutrinos Still denser state ofmatter than electron degeneracy Sun 1000000 km diameter White dwarf 10000 km same diameter as Earth I Neutron star 20 km Degenerate pressure ofneutrons can suppon stars up to 3MG ms of neutron stars Radio intensity Time gt Originally found repeating radio bursts emits light in b Dozens now known Pulses repeatwith 0 001 to 10sec periods Rapidly spinning neutron star I earns Up to 3x mass of Sun i i Size of Lansing gt i 39i l s Highespeed time series in visible light Pulsarnexttua iai i Spins 30x per second Possible ending 3 a black hole ForM gt 3M3 Further collapse black hole Mass is so concentrated that light cannot escape ZGM R becomes greater than speed of light photons can t escape v maps Gravity 133 I Kepler The planets move in ellipses with P2 etc Didn tknowwhy I Newton 3 laws ofmotion affect everything F ma etc Gravity force Gmm2r2 I Geneml Relativity Gravity distortion ofspacetime General relativity I Worked out in 1907 1915 Consistent with incorporates special relativity Describes motions of objects in presence of gravity Gravity distortion into extra spacelike dimensions see Fig 13 12 I Imagine a bug constrained to that 2D surface How many dimensions do we live in I General Relativity I 3D space surface in a 4D space I Use easily visualized analogy I 2D surface in a 3D space I Doesn t know 3 dimension exists Venus according to Galileo Th e Atmosph ere Venus Earth meltingp Sulfuric acid cluud layer Veneva 7 item Veneva 91 n 1975 Veneva 1112 19 v n2 3 r I 39 1 39 Jm 1mm 39 r u 39 we A atiiEPariA Oar usmw Hnnu Hi I n uuxt ThEViverurnVeneraM Mammy sample basalts Some Surface Temperatures in HF Mercury Mariner 10 BOOF Venus Mariner 2 Venera landers 900F Hell Revelations 218 But the fearful and unbelieving shall have their which bumeth with re an bailing pernt ufbnrnstune sulfur ESZF The Greenhouse Effect on Earth inhospth u a re Lmri lnledla 1n mmebv 39 Wemumisvmnvuv r are memes hm The Runaway Greenhouse Effect Suppuse Venus started like Earth co unginally dissulved m ueearrs uv cumhined with me s M DdES L extra heating Mere co2 and H20 in air Mere heating 3 H20 o Hydrugen aturns Escape frurn gravity field Atmosphere evolves no going back The surface of Venus rrnpacr crarers 7 A age dauer of surface unryrswa as marry crarers as unarmarra 90rdestterrarn onry 75E mrHron yrs ord cumpare m3 8 errun yrs urr Earrh Interior Structure Srmrrarru Eanh rrun cur237EE mrres m drameter manrre Muhe Crus1 Tectonics umw u Nup msasuquot a arrymmrsmr h Emmuch shearmg cumpressrunands rerchmg er crus1 bycunvemrun currems m mamre Haspushedup cummems Aphrmme anm ar The surface of Venus rrnpacr crarers 7 A age dauer of surface unry 15 as marry crarers as unar marra 90rdesrrerrarn my fan when yrs org cumparem 38 errun yrs urr Eanh Radar rmages er crarers The surface of Venus 7 41 rmpam crarers age garrng of surface unry 15 as marry crarers as unar marra 90rdestterrarn my fan mrHron yrs are cumparem 38 errun yrs urr Eanh Consfarrtresurfacrng by yorcanrcacrron h n Same smr gumg an r we a Pancaka wtanass Carma wremam lvarvmrckrava amarmagmachambar Mars Some oflhe 19 space that have gone to Mars rarrrr rrrrrg r ram parrmrru ram rm Computing the structure of the sun Measured Properties Want to know at every point within Sun Diameter 109 X Earth Densit Mass 333000 X Earth Temperature Pressure Luminosity 4 X 1026 Watts A e39 45 billion years Chemical composition Surface chemical composition Energy generation Use equations expressing the following ideas 0 The Sun is a gas 0 The Sun is neither contracting nor expanding 0 Each point inside the Sun stays at a fixed temperature 0 How energy generation rate depends on density temperature composition 0 How energy is carried outwards The Sun is a gas pressure is proportional to density x temperature The sun is neither contracting nor expanding Pressure support from below gravitational attraction towards center Fig 10 2 Involves 0 density pressure 0 mass interior to point at each point in Sun Energy transfer 0 Possibilities are Radiation photons light travel a short distance 7 absorbed by atoms c 7 reemitted Fig 108 7 random walk Convection hot bubbles rise cooler bubbles fall occurs when pressure changes very little with temperature Conduction Not important in Sun Resulting Model ii 39 g2 energy 1 2 generation I cumulative nil WW a D 1 Ihmw 16 million deg K n 7 ml quot temperature 0 H i density nl compos1tion l r i 160 x water l m1 4He l E m 39 1 J oi rm K i 2 g i 3H radiation 0 nVeC n numuzmmasmoinlmi munVD i l mass P i i cumulative g u trauSPOIT i 1 39 a N i MTi7 u 73 u 07 IX 7 v 0 i Balm Havana um Q The pressure at the center of the sun is huge 25x1077 atmospheres but the density is modest only 160x water What other parameter plotted here causes the pressure to be so high at the sun s center 111 Kcummauve l Muir a A Temperature ml I nif39nl39b39g39 I I B Radius 0 1 quot 12a 39 C Helium composition 16 miiiion deg K 777 gt iquotquot39 39 w H l l temperature i density l compos1tion 160 x water ia 4He 5 i Lquot a b u 5 2 iHe m K m S u 1 1 73775 rm I am 3 2331 39 I radiationWc nvecti m W W Wm jji mass 5 Energy 33 cumulative transport i l 39 1 in i 67 i 1 av i moamrrtu u M 5 in u as a m u in quot3939 Ia The solar interior Fig 10 3 Radiative energy transport Convection Central Conditions Temperature 1 5x107 K Pressure 2 5x1011 atm Density 162 gcm3 H by mass 0 336 He 0 643 Overview of Solar System t sa intatingdisk wists u t s mus1iy H 75 H2 23 AA We nanets um mommaquot at Sun evads uuuuu m e i km m an mmmm m Giant pianets Tenes1nai vs Juvian Ruck vs HHeice uvianpianetstiumuie i W Kcnie J riceom HoHe eas an up Asteroids 91 Smaii iucky uibitaiuundtheSun es with sizes s iZEI miies Z knnwnnn 8 comets ZSDDEIEIcuiientiyhavedesignatiuns esimaiee s miiimnasemms gt1 miieinsize Muun Tutaimasspinbabiyiessthanmassut leftover The Asteroid Belt Between Mars ampJupnei a 2 273 3 AU inciud2s75 utknuwn as12iuids Mus1iy mm sun in same diiectiun as pianets m piane utsuiai system Fig 93 Jupiter 5 tidal effects are important 433 Eros Ept a pianetfrum farming em W W n it i 2 a 3 Near Earth as12iuid quot quot 113in178AU 22 x9 XE miies quot L I NEAR spacecia uibitedtuii yeai than ianded Feb ZUEH ewes werequot Mis tII Gaps in asteroid belt correspond to 39 esonances Science guai he icai composition a Is as Ems mm di erentiated A No iii Jupiter s in ads at unprocessed m aieiiai train the Sniai Nebuia Li is i z 3 i 5 n y a WWW i i mimmim i Fig 9 m H1 We Final Exam Thursday June 26 230330PM BPS 1410 the regular classroom 0 40 Questions 39 Roughly 10 covering material presented on June 24 39 Roughly 25 based on questions you have already seen on quizzes 39 But about half of those will be varian39om of the question that was on the quiz 39 Roughly 5 new general questions about whole course 0 Review session before the nal Will cover viewgraphs thatwill be available in advance on web Starts at 1240 in regular classroom BPS 1410 Will go for about one hour Then I will be in the classroom until the start of the nal available to answer questions Hubble s Law 1929 10000 Velocity in kins Fig 2518 120 3 a Dvsxanoe in mmions a LY a 1 1 1 so so so Distarwa m mllllans m or r I m 0 Measure radial velocity v from Doppler shift 0 Hubble s Law v HD 0 Proportionality constant H0 is called Hubble constant 0 Note huge change in measured value a m m M n m of Ho between 1931 and today 0 1600 39 Constant re nement of distance scale mumquot on v um today mm mm The Cosmic 390 Distance Ladder h M31 M33 2500000 LY 100000 LY The relatlve dlstances Milky Way The Cosmic Distance Ladder Parallax 20 pc 65 LY 0 SUN P NEARBY sun 11 N uclear hJIge The Cosmic Distance Ladder 65LY Radius Parallax 1ncludes sci ne pulsating Variables 39 20 pc 65 LY The Cosmic Distance Ladder Parallax 20 pc 55 LY Calibrate luminosities of Pulsating Variables Map rest of Milky Way Nuclear bllge Glnbular Clusm some n5 0 2 5 D an Perioddays The Cosmic 9 Distance Ladder M9 M31 M33 0 Parallax 20 pc 65 LY Calibrate luminosities of Pulsating Variables 0 Map rest of Milky Way 2500000 LY and out to M31 Measure luminosities of 0 Brightest stars 1 0000 LG 100000 LY Brightest globular clusters 100000 LG 0 Brightest H 11 regions 100000 LG 0 Etc 0 can now measure distances to more distant galaxies Milky Way Modern methods of determining distances Table 252 Method Distance Range millions of LY But these Pulsating variable stars 065 4 an I t d C 1 ra e Cepheids with Brightest star in galaxy 0150 parallaxes Planetary Nebulae 07 0 Globular clusters 0100 C hbmted gt Rotation velocities 0300 With P sa ng gt Supernovae 08000 variables Brightest galaxy in cluster 7 013000 H clallbrat3d W1 Redshifm Hubble Law 300 7 13000 4 supernovae rotation velocities etc Measuring Distances using Redshifts I I I 30000 0 Measure Doppler shift from emission or absorption lines 20000 Velchly km sec Redshift Z Vc coco V into Hubble s LaWZ uo mo zoo ago 400 500 DIslance Mpc V HO 1 d vHO The Expanding Universe Ieza w 2 3 III Distancegt We are unlikely to be at exact center Scale of the Whole universe is expanding Galaxies all recede from each other 0 Except for small random motions But galaxies do not expand internally Held together by internal Fig 25 20 gravitational forces I The Shape of the Universe Cosmological principle 39 39 39 Universe looks the same from any point Expanding Universe Hubble s Law g W p Scale Factor Rtime Rt gt Distance Rt x comoving distance we 5 m m m Dlstance gt Rt increased by factor 2 General relativity Worked out in 1907 1915 Consistent with incorporates special relativity Describes motions of objects in presence of gravity Gravity distortion into extra spacelike dimensions Figure 162 Rubber mlll l l analogy for curved spuro around the Sun Some possible geometries my ZERO CURVATUHE POSITIVE CURVATUHE NEGATIVE CURVATURE For the particular case of positive curvature A particularly large Black Hole So solutions do exist for uniform matter distributions Geometrical Tests amp 2 Viaquot x z OO V v wig 17 51 Curvature Curvature a zero curvature Positive curvature light follows closed path Fig 285 The Expanding Universe 0 Light waves get stretched redshift 0 Individual galaxies do not get stretched Fig 286 0 This example has positive curvature 0 But same true for other curvatures In spite of these examples positive curvature is not the preferred model The Evolving Universe 0 Formerly concentrated in a tiny volume Kinetic energy vs gravitational attraction Curvature of space Evolution The search for until recently two numbers Ho 90 rate of expansion qo Change of rate of expansion Fig 288 Scale of universe F closed I open Time 4 To 2 Past Present Future Energy balance 90 Curvature Future kinetic gt gravitational lt 1 negative open kinetic gravitational 1 at critical kinetic lt gravitational gt 1 positive closed Expansion causes redshift Lookback time Looking back in time test theories of evolution 0 Stars 0 Galaxies 0 Larger structures But models are in units of years We measure redshift z Redshift scale factor RU L 1 Z Must use cosmological model to find how R depends on t Scale of universe I 1 closed open 0 Pas Present Time 4 Future 0 Everything definitely is But is the universe really expanding moving away from everything else But maybe matter H atoms is constantly being created throughout the universe Steady State Theory FredHoyle 1950 s Velocity km sec 30000 20000 10000 100 200 300 Distance Mpc 400 Proof of expanding Universe Universe used to be smaller Scano wwusa n 0 Denser Hotter Most normal matter is hydrogen 0 Was fully ionized at earlier times m m gmquot 0 Photons could not travel far 0 Absorption by free electrons H Matter and photons intimately linked together Cosmic Microwave Background Hotter 0 Hydrogen ionized Universe opaque 39 Photons travel only short distances 0 Absorbed reemitted by free electrons o Pimwg biiiiisago Universe 300000 yrs old quot quot9quot 0 Hydrogen becomes neutral p e H Universe becomes transparent Photons decouple from matter continue in whatever Cooler direction they were moving Expansion of universe redshift Photons formed in blackbody with T N 30000 K Redshifting lower energy per photon E hv hc7t So we see T 3 K blackbody spectrum Discovered in 1965 Fig 2815 angmnass 1 v I Wavelength m Pen21as Wilson and their radio telescope 005 01 Summary How do we know the universe is expanding from a very much smaller size Hubble s Law Cosmic Microwave Background CMB Isotropy of the Cosmic Microwave Background 0 COBE satellite Blue 0 K Red 4 K Blue 2724 K Red 2732 K Dipole Anistropy motion of Sun through Universe WholeSky Maps Hubble s Law 1929 20000 ms 0 Vexacny m k Velocity in km 5 8 Fig 2518 20 3 a DistantE in mHlions a LY a l l l 30 so so Distance m mllllcns m or r I m 0 Measure radial velocity v from Doppler shift 0 Hubble s Law v HD 0 Proportionality constant H0 is called Hubble constant 0 Note huge change in measured value a m in Mn 1 m Of Ho between 1931 and today 0 1600 39 Constant re nement of distance scale million on v Jun today mm m The Horizon At any time we can only see as far as light can have traveled within age of Universe 0 Present age ofU 14 billion yrs Universe presumably is much bigger than this At earlier times we could have seen only a smaller fraction of the Universe The Horizon Problem Causality How can parts of Universe that never before communicated know how to have almost exactly the same conditions What happened back at the Big Bang Density nsa erEE 9 1 IL e 11 m hm O Nb 5 9 Scale Factor al 7225317215507A0125A017 gmcc The Flatness Problem 20 close to l at present time 0 But this requires incredible precision at start t 0 QO exactly 1 The solution In ation probably maybe 1060 Extremely rapid expansion of 1040 Scale of observable 39 universe standard unlverse E 1020 big bang model o 8 0 due to release of energy E i m in phase change 5 10 2 l Scale of observable 39 I universe inflerionary B 10m model 0 like ice to water 1050 if15 1045 1045 1045 105 105 10 5 Universe becanle Time Seconds Present 1943 Itimes larger Fig 2817 Within 103932 seconds Freezing out the forces Time after Temperature Big Bang of iiniverse 1043 Grand Unified Theory 1027K 10425 10 s Fig 2816 Wcll nuclear mu 5x10 5 know Phase changes and latent heat Apply heat energy at a steady rate to a xed quantity of H20 How does the temperature change Temperature Sn ercoolin P g Fame What does in ation predict for geometry of present universe Smlenl maemame my standard Universe became g to blaming made 043 times larger 5 g 3 Wm Seal lob u W1thm 10 32 seconds D runlvgrgetlnliziroana y In We an quot Pred1cts a at umverse r 7 7 YDquot H I075 V0 quot I0quot I QB 1000000 Tm month As far out as We can see I red circle horizon most distant place from Which light has had time to travel quotg g g i quot A er In ation Solves atness and horizon problems But there is insufficient normal matter to presently maintain a at universe efore In ation out out Weak nuclear forces 10quot2 sec 10 5 1 sec 109 3000 Where did H He and Li come from 6mm lvv Nucleosynthesm 1n the big 9 gig b 3 mar quotN 39 First 3 minutes w39rsmm C7 n iquot u pm 39 Fig 2811 neutrinos freeze out wam g gt positrons electrons freeze out gt quot helium syn esis 39 M Newman 10 decoupling 9gt n m of CMB U f w m 3 m5 04 5 F m W V 1 5 0 i 0 IO 1 w m m 5 1 Age at he Unwevse 59001165 Present Fig 2812 Tampevaluva K Where did H He and Li come from Exact mix of H He Li is sensitive to exact density at time When T dropped below 900 million quotK Ratios of HHe DH tell us density of ordinary matter 003 x critical density neutrinos freeze out o s 1 105 s W 0 5 Agsm the Universe l ecunusy Pmsenl 102 com o m nmsmr mum 5 umum 4 u newsan Weak nuclear forces CMB out 1035 sec 1027 10 5 109 3000 10quot2 sec lsec Structure within the Universe The Local Group 0 Our Galaxy and its satellites Andromeda galaxy M31 and its satellites Tna Localeup NSC quot I I O lt NGC 185 I lt Fulnax Fig 273 Mltky Way W I O lt Magellanic Clouds I ltIC 1613 Galaxy Clusters 1000 s of galaxies Coma Clusler HST WFFCZ Structure upon structure Fig 277 0 Local Group is in orbit about Virgo Cluster 1014 MG 0 All part of Local Supercluster 1015 MG Structure upon structure PerseusrPisces Local Supercluster T Fig 2720 Great mquot Milky way Local Group is in orbit about Virgo Cluster 1014 Me All part of Local Supercluster 1015 MG Local Supercluster is part of streaming motion towards Great Attractor 1016717 MCD 0 located 45 Mpc away Detected by extra motions superimposed on Hubble Flow Bubbles and Voids Fig 278 u Occasionally causes trailing of radio jets Measured from xrays see Fig 279 Gas between galaxy clusters Hydrogen emission line W in SO at redshift 26 Ema Hundreds ofhydrogen E f absorption lines due to gm gas at lower redshi s we a mo am am mwamiil39im Detected by intervening gas clouds absorbing background light from distant quasars QSOs The Distribution of Normal Matter Location Fraction of critical density Gas w1thln galax1es 0001 Total normal Gas in galaxy clusters 0003 mm 01722 Big Bang Stars Within galaxies 0004 Nucleosynthesis predicts 003 Gas between galaxy clusters 0014 Dark Matter Motions in gravitational elds much nonluminous matter Observed Sun39svernmyis ZED ebuurZZUkmsec 0 On scales of Diffemn by the dark mane hare e Within galaxies verneuy K may 150 mm 0 Galaxy clusters Superclusters Rotation Velocity Kmsec r r n 5 lEI l5 2U 25 3D Distance rum Center Kpc Example mass of Milky Way as determined from Sun s motion Missing Matter actually discovered in 1933 Fritz Zvvicky Motions ofgalaxies Within large clusters Rapid motions larger cluster mass than suggested by luminosity of galaxies Gravitational Lenses 1938666 Another way to measure total mass in clusters see 264 radio The Einstein Crossquot Galaxy at center causes 4 images of same quasar Gravitational Lens in Galaxy Cluster A611 22 l 8 Foreground cluster disrts images of numerous background galaxies Use to determine total mass of foreground cluster Shows that 85 of mass is Dark Matter The Remarkable Case of CL00241654 Single distant blue galaxy Lensed by foreground cluster 8 different images Allows detailed analysis of mass distribution in cluster 83 of mass is nonluminous Dark Matter see Fig 2623 The distribution of all matter Location Fraction of critical density Gas Witlun galaxies 0001 Total normal Gas in galaxy clusters 0003 mm quot022 Big Ban Stars Within galaxies 0004 Nucleosynthesis predicts 003 Gas between galaxy clusters 0014 Dark Matter 03 90 of all matter is dark matter What is Dark Matter Light fastmoving particles Neutrinos recently discovered to have mass 0 But only 1 of total mass Super Kamiokande Japan 0 Large chamber deep underground Neutrinos interact weakly with water 13000 photocells detect resulting light 0 Found neutrino oscillations Three types of neutrinos known Neutrinos change back and forth between types while in transit Can only happen if neutrinos have mass What is Dark Matter Light fastmoving particles Neutrinos recently discovered to have mass 0 But only 1 of total mass Massive Compact Halo Objects MACHOs Large Ruled out by grav1tatlonal lensmg test Magellanic a i r 1 Cloud Orbiting MACHO crosses our lineof sight Gravitational lensing causes brightening Glol mlarclusler What is Dark Matter Light fastmoving particles Neutrinos recently discovered to have mass But only 1 of total mass Massive Compact Halo Objects MACHOS Ruled out by gravitational lensing test WeaklyInteracting Massive Particles WIMPS Current best bet Being searched for here on Earth Formation of Structure Blue 0 K Z COSIUlC Microwave Red MK Background is extremely smooth Blue 2724 K lt 05 density variations when Red 2732aK universe was 300000 yrs old Present universe is very e um Py 100 density variations Insuf cient time to go from one to the other through gravitational growth of density perturbations Formation of structure 0 Dark matter is necessary 0 CMB only traces distribution of normal matter 39 Light does not interact with dark matter 0 Dark Matter must have already condensed into clumps by time of decoupling Computer models with Dark Matter can reproduce observed type of structure The Cosmic Web Recent calculations from the National Center for Supercomputing Applications F lythrough Growth of structure Cannot get models to match observed structure unless 90 of matter is dark matter Formation of the Galaxy Collapse rotating disk Halo Globular clusters amp halo stars formed during collapse 0 But many details are uncertain Bottom Up Galaxy Formation 89 Small structures form rst it 0 Dwarf galaxies Clcluilrulgnlaxlei Globular Clusters Galaxies grow by cannibalism K 15quotle mums 2 Gllule Now Ellipticals formed by mergers of spirals Fig 2718 Our current understanding is incomplete 0 Both topdown and bottomup formation seem to play a role
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