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by: Stephan Gorczany


Stephan Gorczany
GPA 3.9


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Class Notes
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This 38 page Class Notes was uploaded by Stephan Gorczany on Thursday September 17, 2015. The Class Notes belongs to AST 1002 at Florida State University taught by Staff in Fall. Since its upload, it has received 35 views. For similar materials see /class/205665/ast-1002-florida-state-university in Astronomy at Florida State University.




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Date Created: 09/17/15
NON SEQLllTUR Wh a t IS A s tro n o m y T awe lx TRONolM NJRONOW Wig EliFORE NE kgkoLocx E if mm RE 4 Astronomy IS the study of obJects beyond g g the Earth s atmosphere and of how these objects interact IMPORTANT This is a science class It uses the tools of science namely math WeexpecLyoquoJoeabletddo mathemat bprous calculations Also malls ELCO i T0 Lou 1 NOT an atrt l gmy 3 WW t EGFOKE NE pl k Y ROLle wll not leg nggggp i 2 5 stellations othe tii t a posts to guis 7 E sky quot quot a What Is Astronomy 777 IMPORTANT This is a science class Also IMPORTANT This is NOT an astrology class We will not learn about the constellations other than as signposts We will learn How we know about astronomy techniques and tools What we know about astronom our neighborhood the solar syste the stars and their cycles the distant galaxies What we need to learn more about there are still paradoxes and unanswered questions G W W Norton and Company Astronomy 1002 Grades Grades will be determined by Quizzes 1500 3 one hour exams 1700 each Final Exam 4 There will be approx 10 12 quizzes randomly throughout the semester We will drop the 2 lowest quiz grades Extra credit can be earned by answering questions during class or by answering extra credit questions posted on the course webpage I ll give you more on this later l Gett39 gHelp If you have questions Q Ask during class Send me an email lindmagnet fsu edu Call my office 6441576 Come to my office hours Mon amp Wed 1230130Pm Set up an appointment Stop by my office any time I39m in Check the Course websi httgwww icsfsueduuser39sLindlasthOZ defauthtm Also the textbook is a good place to get more information Sc en Method irsr orma iZE by Galileo Gallei Based on testing and experimentation Make a model hypothesis Test the mode Observations Experimenm Modify the model if necessary etes Improved techniques Better experimenm Don t accept things on faith look for evidence But remember science is done by people we make mistakes and have biases too Cosmological Principle There is nothing special about out place in the universe The Universe is isotropic it looks the same in all directions The Universe is homogeneous any large volume looks the same as any other large volume at the same distance N a large volume since there are small scale variations like us Without the cosmological principle you can not study the universe as a whole only the parts you can see 0 Laws of Nature The rules describing how the Universe behaves The ultimate promotion for a model Same rules apply everyw er ex mple gravitation motion etc Subject to modification eg Newton39s laws governing motio Work perfectly well for objecm not movll lg really fast For really fast movan objecE need Elnstell39l39s theory of relatlylty B 9 and Small Numbers 7 Really big and really small numbers are hard to understand Exampe how many are 1 10 100 1000 10000 100 7 000 1000000 Have you ever seen a million of anything If I offered you a million dollars to co unt to a million would you do i How about a illion We will often use powers of 10 for large and small numbers 0000 10x10x10x10x10x10 1 5 Each factor of 10 is one order of magnitude L Really B 9 and Small quot 39 Really big and really small numbers are hard to understand and work with It takes a LOT of zeros to write some numbers A million billion is 1000000000000000 Easier to use powers of 10 A million billion has 15 zeros which is 1015 5 million billion is 5 x 1015 Small numbers use negative powers of 10 A million billionth is 10quot 0 Measu ng Distance Metric units Meters m and kilometers km 1 meter 3 28 ee KllOmeter 1000 meters 103 meters aboutO 6 miles 1 mllllmeter 0 131 meters 10quot meters Astronomical Unit AU Average distance from the Earth to Sun 150 million kilometer Lightyear LY The distance light travels in 1 year Light travels at 3 x 10E ms in a vacuum 186000 milessecond 7 times around the Earth lri a second r ghtyear So in a year how far does light travel There are about 3 x 107 seconds in a year39 60 3 x 60 x 24M x 365 yr dimenylealmyyly s 316 x107 syr Light travels at 3 x 108 ms or39 186000 miles s and Distance rate xtime So Xm7XX gtlt m 9 X 1012 km 6 x 101 186000 miless x 3 x 107 s 2 miles Lightyear cont AcTually 1 LY 947 x 1015 m 1016 meTers Ten Trillion kilomeTers 236 000 000 Times around The EarTh Sounds far buT we39ll see some really far disTances The nearesT sTar is 4 3 LY away IT Takes lighT one year To Travel 947 X 1012 km If you were 1 LY away and flashed a lighT we wouldn39T see iT for a year The sTarlighT we see TonighT was emiTTed by The sTars many years ago Lookin inTo The sky is looking aT whaT happened in The pasT he furTher ouT you look The farTher back in Time The sun is 8 lighTminuTes away from us If The sun exploded righT now we wouldn39T know for 8 minuTes Tour of the Universe 39s a39miamea Proximal Centauri The closest star in our Sun alga arms Sun a r h1 39 39 ilkquot We Jll llalallcy ll 42 years i f I 41333 V 4 a 39 1l patina years Earth a Galaxy 411 Milky Way Galaxy 14 blllllarg years a 135 Radius of the observable Universe Tour of the Universe PlaneTs EarTh JupiTer Mars Venus SaTurn STars The Sun NorTh Types of STars Types of STrucTure in The Universe Galaxies Nebula Clouds Supernova WhiTe Dwarf Red GianT Types of Galaxies Spiral EllipTical SuperclusTers STar Alpha CenTauri Dwarf Radio Mercury AST1 2 Planets Stars an Ga aXIes Terresmal Planet Interiorsquot dav s Lecture purpose ampgoals n Comparative Planetoloqv learn by comparing planet s properties Understand the concepts of 1 History of Terrestrial Planets Four major processes differentiation cratering volcanism weathering and gradation 2 Density p MV 3 Heat Transfer Venus x x Review 4 Pieces of the Solar System Sun in a few weeks Jupiter Mars Earth Venus Mercury inner terrestrial planets this week outer jovian planets next week other stuff following week Angular momentum Annlll u MAMAHLIIM n nAnnAul39l A Pluto ranus ms a LIITI HR ma Introduction Terrestrial Planets Comparative Planetology 339 Small rocky worlds Mercury Venus Earth Mars can also include Earth s Moon Helps us understand Weather Earthquakes Climate Basic Facts about Earth Radius About 6400 km Shape Oblate spheroid Polar radius 21 km shonter Composition Mostly made of materials denser than rock The average density is 5520 kgm3 Measuring the Earth s Mass In order to compute the Earth s density we need The Earth s radius The Earth s mass To measure the mass we need to consider Newton s laws of motion Newton s law of gravity Newton 5 2nd Law Newton s Law of Gravigy m Radius of Earth is measured to be R 64 x 106 m Newton s constant is measured to be G 67 x 103911Nm2kg2 The acceleration due to gravity at Earth s surface is measured to be a 98 ms2 Mass of Earth e M 6x1024kg Density Mass Volume Radius of Earth R 64 x 106 m Volume of Earth v 41tR33 V 11 x 1021m3 W Structure of Earth r Crust Solid thickness 35 60km silicates Oxygen and Silicon compounds Mantle Plastic thickness 2800 km silicates Oxygen Silicon Iron m r lwmum de39vs lly Outer Core Liquid thickness 2400 km metallic Iron and Nickel Inner Core vlglo lulmrmeve ems and paquot oi mantle Solid thickness 1200 km metallic Iron and Nickel The density is about 14 gcm3 Temperature 5000 K mm c cm wng denswyl Planet Interi0 The inner planets all have sir structure although we don t have a lot 0 other planets Data on Earth s interior comes seismic readings of earthqu P waves Compression waves like sound waves the waves oscillate along the direction of motion of the wave These waves can travel through solids and liquids S waves Transverse waves like water waves the waves oscillate at right angles to the direction of motion These waves can travel only through solids Planet Interiors I Layered solid inner core liquid outer core solid outer mantle crust Hotter inside cooler outside center is hottest and has highest pressure planet radiates heat into space Larger Planets cool more slowly outer crust cooled and hardened Melting point depends on temperature and pressure in the center pressure wins and material is solid farther out temperature wins and material is liquid outer edge both lose and material is solid quotmm Interior Heating Radiative cooling alone should have cooled lhe Earth s interior more than observed Friction adds some of the heat tidal forces due to the gravitational pull of the Moon and Sun cause pieces 0 the interior to ru to ether this rubbing generates heat just like rubbing your hands 0 e r Radioactive decays add most of the heat The interior temperature is a balance between original heat radialive cooling and addilional heat I As the radioactive material disappears the Earth39s interior oools Differentiation During planetary formalion the rocks and planetesimals compress together due to gravity Gravitalional energy ofinfall is converted into heat material melts and becomes ui Differentiation is the prooess ofheavier denser materials sinking towards the center of the planet while lighter less dense materials rise to the surface materials become separated by type Outer surface of planet cools fastest and hardens Crust Formahon Magnetic fields Inner planets all have some magnetic eld 111is magnetic eld is not caused only by magnetiled ma erials In Earlh At least partially caused by rotation n r quot i ui magnetic field Dynamo Efflect Earth has a strong magnetic field rth39s magnetic field moves with time magnetic north pole not the same as celestial nort po e r the Moon has no or very small magnetic field Me ury ha oderately strong magnetic field few 00 of Ea rth39s field Venus and Mars have small magnetic field urmrm n a mgnclrzmm Am in Four Main Processes These processes shape the surfaces of planets 1 Impact Cratering meteors hitting a planet39s surface 2 Volcanism nquot flow of material lava from beneath the planet39s crust plates 3 Tectonism LA 39 Ill A JulA Impact Cratering The number of collisions between objects depends on how many objects there are gt Early in the Solar System there were many more small planetesimals many more collisions Number of craters can be used to date a planet Craters can be erased by tecton ism volcanism land gradation m occurs on active planets 397 eg Earth on dead planets craters remain eg Moon Formation heats and compresses material thrown outward surface rebounds Comparative Cratering Moon amp Mercury many craters of all sizes Mars craters with water channels indicate there might have been water on Mars once Venus dense atmosphere protects Venus few visible I protected by atmosphere many meteors burn up large oceans leave no visible impacl crater most craters erased by gradation a Volcanism l Fissures in the planet s crust can allow hot mantle to flow to the top lava the mantle is solid but after relieving the pressure from the crust it can turn liquid Long fissures cause shield volcanoes large long mounds of cooled lava to form over long time periods Local holes can form mounds on Earth plate movement limits the size and can result in a chain of islands Large flows of more fluid lava can create great plains of lava eg Lunar mares seas and Earth39s ocean floors Amount of volcanic activity indicates how active a planet is Comparative Volcanism L I MOO mares are volcanic in nature and indicate the Moon once had a lot of lava flow Mercury some visual indications of lava flow not enough known Mars largest mountains in the Solar System up to 25 km high caused by volcanism Venus evidence of significant complex volcanic activity I lots of current and previous volcanic activity Pompeii Hawaiian Islands Mt St Helen39s Major movements of planet crusts Tectonics L creates mountain ranges deep valleys on Earth tectonic plates rub against each other causing earthquakes etc other planets not plates but major cracking shifting fractures KEY C Separaling plains Volcano uto Converging plums Esrihquake Transiomi fault 1 Valle Mnrlnarls Tectonics LI Fault Lines California Europa 9 2w Thalrsonl muls Dole Continental Drift In 1924 Albert Wegener proposed that the Earth s plates are mobile 0 We see similar effect 0 other planets Venus 53quotquot J Mercury Earth39s Moon r39 I Gradation 4L Surface leveling caused by blowing wind flowing water and water ice freezing melting 1 Moon amp Mercury no atmosphere possible ice little gradation Mars large dust storms observed evidence of water flow Venus evidence of blowing wind no evidence of water I all processes present eg dustwind storms rain tides glaCIer flow cwwmmcwny Chapter 6 21st Century Astronomy Norton Media Library Beautiful Sunsets at n Blue Skies Nitrogen scatters blue gt light in all directions across the sky but leaves the redder light largely unaffected 7 When the Sun is low in the sky and less bright we see the residual red light that comes straight at us Crater wall senml peak a w w Norlnn and Cnmpany uApolln 14 cmenng rate Apulln 1s Apollo 11 Apollo 15 Apolla 12 4 393 2 39139 Fresenl Bllllnns 7 years hefnre presem n w w Nanm and Campany Dumvmnlnn A Mumm VampIns E c w w Norlnn and Cnmpany c w w Nnnnn and Cnmpany c w w Norton and company 1O A Brief History of the Solar System Origin of the solar system Solar Nebula Proloslellar Prutoplanetary I Sun disk planets outer planets otherstuff Angular momentum angular momentum is conserved Solar System formation accretion disk rotation protostar Planetesimals and the solar StarBirth Clouds ms 1 quot Wmquot PRCQSMbST SclOFONovembelr21995 l Extra Soar Planets J Hester and P Scowen AZ State Unit NASA Summary The Solar S stem Facts and heories asic Characteristics of the Solar System Planets moons generally orbit and rotate in the same direction Planets lie approximately in the same plane Small rocky worlds aw near Sun large gaseous worlds hafjf further out 3534 Age 46 billion years r 9 J Theory Solar Nebula Theoni created from a revolving sphere of gas and dust The inner region hotter 9 volatile materials did not condense there but did in the outer region Condensation Seguencequot Conservation of Angular Momentum Angular momentum measures the rotation of an object L m39V39r Angular momentum is conserved 9 always the same the larger the size the slower it rotates the smaller the size the faster it rotates to have the same angular momentum nv iv unuxnoez LI 9 20M Tmmml moks Cola Formation of the Gravity and the collapse of Gas Cloud Solar System Current Idea Solar Ne L A u I u y Spiral arms of ga axies are filled with clouds of gas and dust Parcels ol gas Wlllllll a molecular loud the Solar system formed from the collapse of one of these huge clouds of gas and dust The collapse started because of the gravitat onal attractio between the gas and dust part icles in the cloud feel the qravilalional allraotion ol all other parts ol the molecular timid Net gravitational force eading to a net gravitational force toward the Cloud center Formation of the Angular Momentum and the collapse of Gas Cloud Current Idea Solar Nebula Thoery Solar system formed from collapse of a huge cloud of gas and dust The original cloud must have been spinning slowly As the cloud collapsed it spun faster because of the conservation of angular momentum Axis of relation at W W Marion and Company Solar System 2 star Most of the cloud collapses into a disk rather than directly into the Formation of the Solar Nebula collapse to disk 1 The Solar System formed from a rotating disk of gas and dust 2 A star forms when a cloud of interstellar gas collapses IInrInr Hn nuun inrninkl Ina an Protostellar Protoplanetary Sun disk r i uv v V 39 r Solar System 3 iStarligl reflected from dust Silhouette nf disk 7 Condensation amp Accretion Gas motions push small particles into collisions with lFormation of the Solar System 4 larger particles m Aggregates grow to about a 100m in diameter 5M K4 A 1 v l 1 ll 1 WW 3 Weak gvaww 5 name 0 demun small ablecls 1c w w Nonon and Company Formation of the Solar System 5 Condensation amp Accretion 39 Gravity helps planetesimals grow into planets The gravitational energy of the infaIIing material turns into thermal energy heat Formation of the Solar System 6 Condensation Sequencequot I Refractory high melting temparature material remains solid even at higher temperatures Volatile low melting temperature ices survive only in the outer disk but only refractory solids survive condense in the inner disk A miniaccretion disk forms around each new massive planet Rocks and metals condense Hydrogen compounds rocks hydrogen qompoundsstay vaporized and metals condense a Solar Nebula the story plays out quot 7 Rocky terrestrial planets formed in the inner solar system Less massive planets lose their primary atmosphere because fast atomsmolecules such as hydrogen and helium in the outer atmosphere can escape the planet s gravitational pull They then form a secondary atmosphere from cometary infall amp volcanic outgassing The cores of the outer giant planets formed from solid planetesimals as did the inner planets but the outer planets were able to capture and hold many times more gas Moons formed from the miniaccretion disks around the giant planets Asteroids and comets are planetesimals that survive to this day Earth39s moon probably formed out of the debris from a collision Four Main Processes These processes shape the surfaces of planets 1 Impact Cratering meteors hitting a planet s surface 2 Volcanism flow of material lava from beneath the planet39s crust 3 Tectonism movement of pieces of the planet s crust plates 1 n 59 d E 4 Gradation 39 weathering and erosion of the quotW 7 5 i surface Evidence visible on surfaces of Terrestrial Planets and JOVIan Moons Extrasolar Planetaw Systems cl Planets have been discovered around other stars over 100 found in the last three years using the Doppler effect to measure the tiny wobble in the star39s position caused by the mass and orbit of the planet only works for short period small orbital radius massive lanets Earth would not be detectable with our current evel of technology so far two extrasolar planets have been detected that also nonfu rshmb m transit across their star s 9 m quot disk dimming it by a fraction of a percent Unseen planet ExtraSolar Planets L In December 1991 the astronomers Alex Wolszczan and Dale Frail discovered an amazing fact about the star the star wobbled indicating the presence of the massive planets orbiting it star Pulsar old neutron star distance 1300 light years planets 3 Earthsized u 305 m Arecibo dish in Puerto Rico ExtraSolar Planets II Discovery On July 4 1995 after months of careful observations the astronomers Michel Mayor and Didier Queloz became convinced that they had finally discovered the first extra solar planet orbiting a Sunlike star Upsilon Andromedce Their discovery was confirm 2 ed by the American astron omers Geoff Marcy and A 1 Paul Butler who went on 3 to discover many more V 0 39 exoplanets 1 2 2 1 O 1 2 5 4 x Au httpcannonsfsuedugmarcyplanetsearchupsandupsandhtml over 107 0 1 2 3 4 Orbltal Semimajor Axls Ev 2004 Thomsonr ruoks Cale ii 51 Pegasi 39 1L 7quot r PSR 125nm Gamlnga 16 Cygni E V g Rho comma Borealis 55 Cancri Q i g V r I Ursae Hajori V lHD l IslTE Upsilon Andromeda 39 39 9 39 70 Virginia Tau Boole IV s i 7 Eliasg s 7 r nossmsr 39 a Beta Pistons 10 Light YE r Discovering Planet Observations if our lineofsight is aligned with the orbital plane of the planet and its star the planet could block a small fraction of the light we see from the star 3950 210 110 0 0 10 20 350 Relative brightness I Planet Brightness Protoplanetaw Disks found around a number of nearby young stars would be precursors to the protoplanetary disks the lead to planet formation I iii L152 1 IV39 E LI ELI L Summary Solar System Most likelv to have formed from a huge dust and gas cloud about 46 billion ears ago Gravitational attraction caused the cloud to Shrink Conservation of angular mommtum caused cloud to flatten into a protorplanetary disk ExtraSolar Pla nels More than 100 extrasolar planets have been discovered Verv different from our own Solar Svs em Many ow 39 No a AST 1002 Planets Starsand Galaxies Anal zmg Starlight finding the properties of stars Astrometry Todav s Lecture purpose amp goals 1 Measuring the Properties of Stars measuring stars Temperature measuring stars Composition measuring stars Distance measuring stars Luminosity measuring stars Size measuring stars Mass 2 Properties of Stars 3 HR diagrams Observing Stars 4 We study stars by observing their light What can we learn about stars Brightnessluminosity Distance from us Velocity has fastwhat direction Mass Size Composition Ultimately we would like to find common characteristics between stars and learn the how and why of them REVieW atoms amp spectra lecture2 I is quotgll39llaveleng39lh Properties Of waves El mpi u wavelength frequency period speed Light is an electromagnetic wave different types of light correspond to different wavelengthS Frequency l lertz 3x10 3x1019 3x10 3x10 3x10 3x10 3x10quot 3x103 Ehvhclk 1039 111 1quot 109 111quot6 10quot mquot5 141139s 1mquot 103 102 1aquot 1 7 7 in Wavelength m Atomsenergy levels absorption and emission of photons Doppler effect Vrc AM Temperature and light all objects emit light blackbody radiation hotter bluer amp brighter is Temperature and Light 7 A 4 All Warm or Hot objects give off light Temperature is a measure of how fast the atoms molecules are moving hot atoms move faster than cooler atoms faster movement means more collisions Collisions of atoms can convert internal energy to light This is what causes an incandescent light bulb to glow Temperature and Light All objects radiate light that is dependant on their Planck spectrum I A continuous Planck spectrum emerges from the hot interior of the star Wavelength K urn gt Intensity gt 39 oes up by a factor of 16 24 r er light Ace 1T i l to the inverse temperature mperature the wavelength drops in determine temperature edium and red are cooler Measuring Stars Temperature I blackbody radiation I Two equations describe the temperature dependences of blackbody radiation Wien s Law L 31 6000 K Apeak x 048 pm V i 1 Making an object hotter makes it more luminous lT K and shilts the peak of its Planck speclrum to shorter wavelength Stefan Boltzmann Law 39139 1 5000 K 058 m total Luminosity of a source L surface area x energy emitted per unit area 41tR2 39 E 39 0T4 where o is called the Boltzmann39s constant 6 567 X 108 Wm2k4 o 05 10 15 20 25 3 Wavelength Alum Intensny gt 1 4000 K Ape 073pm 739 2000 K Am 145 um Measuring Stars Composition I Stellar atmospheres are cooler than the opaque interior of the star the atoms there absorb spectral lines corresponding to transitions between atomic energy levels give us the star s composition Figure 128 Tu n39marion of absorption and 01155107 ll105 m the sperm Qfxmrs Wavelength K um gt 035 040 045 050 055 060 065 070 Wavelength um 39 Stellar Composition 1 Stars are primarily composed of hydrogen and helium Others are trace elements All 92 naturally occurring elements in Sun and stars like it Population 1 2 heavier elements Some stars have essentially no heavier elements Population 2 Here s a sampling of composition Element Percent by Percent by Number m Hydrogen 925 745 o Helium 74 237 o Oxygen 0064 082 Carbon 0039 037 Neon 0012 019 Nitrogen 0008 009 Iron 0003 013 Intensity and Luminosity quotl Inverse Square Law of Light Luminosity is the total amount of light given off by an object Intensity is how much light we observe if an object radiates light evenly in all directions the intensity goes as 1 r2 r distance from the source think of a sphere 7 We can use the observed intensity to measure the distance if we know I the luminosity 5 539 quot or vice versa I Brightness in unit Stereoscopic Viewing To determine distance to an object we view it from 2 different places see how it moves with respect to far background this is how our eyes work and how surveyors mmsure distances In astronomy we view stars from different parts of the Earth39s orbit around the Sun close stars will move a lot farstars will move a little Measuring Stars Distance parallax By measuring the angle by which the star moves we can determine the distance Angles 1 degree 60 arcminutes 1 arcminute C 60 arcseconds 1 arcsecond 13500 degree Distance 1 parsec 326 lightyears ied direction m svlcr view loww a my auxin xur Measuring Star39s Luminosity 7 We measure a star s brightness by how much light e see We have just measured the star s distance parallax Therefore we can calculate luminosity inverse square aw Ibrightness Lluminusity4 rrl 2 r distance to star luminosity brightness X 4an Ill39il39rrl 2 We have measured the luminosity of many nearby stars Our Sun is more luminous than most Last luminous is 0 0001 tims our Sun Most luminous is 105 times our Sun a Measuring star s Size M Once we know the luminosity and 2 4 temperature we can measure the size 39 4 R 6T luminosity surface area x constant x T4 surface area 4an r radius of star luminosity 4 Tcr2 x constant x T4 we can solve for radius and calculate it radius We have measured the size of many nearby stars Most stars are smaller than the Sun gmallest stars are 001 times the size of the un Largest stars at several thousand times the size of the Sun Determining the star s Mass I Star 8 speclmm at mm 1 appioaclwzg therefore biueshillod Determine the mass from the effects of gravity Kepler s Third Law Use binary star systems two stars orbiting each other J follow ellipses with a shared focal point Siav B Speclwm at me measure velocities or separation amp period quotom Visual binaries Close enough and widely enough separated l that we see both stars Spectroscopic binaries use Doppler shift velocities Eclipsing binaries gab go one passes in front of the other and brightness V W size accurately app em nngmness changes can also be used to measure star39s A A A A a i is l EC 1911 35 l l3vji 1040 13935quot v y me Classification of Stars Classify stars by temperature Classes 0 B A F G K M Qh e A fine guygal Kiss Me 05 150 quot u 30000 1540 9520 3200 7201 0 blue are the hottest stars M red are the coolest stars The Sun is a 62 class star Spectral types 5 L a a ammadum enacting 571m 5250 V use 3550 3244 035 0441 050 1160 070 NearUlf Wavelength am NearlH Elnar Hertzsprung Denmark 51 Henry Nams R ussell u s Compiled data on stars Plotted luminosity vs temper Astronomers consider this a very important plo HR Diagran woman In mama w 39 0 Rm q mmmun mm mm mm mm mmm m swmumijIlZijjq as an as u rum s as E mquot coymy i i i y yi m 1 u 393 35 m lGalaxies April 2 2003 I 1 Introduction 1390 Galaxies I 0 2 Types of 39g I 39 Galaxies quot u39 1 3 T 39 S 39 0 he Milky Way 4 Dark Ma r rer u I u39 I t o I I 39 I httpwwwhepfsueduNtadamscoursessprO 5st10027Lecture040203pdf g Messier Objects 1784 Charles Messier he was a comeT hunTer IdenTified 103 objecTs in The sky which were noT sTars 1 Crab quotEbular These were fuzzy objecTs he idenTified Them so They would noT be misTaken for comeTs These were acTually galaxies globular clusTers and such far away Now a very useful lisT of inTeresTing objecTs for amaTeur asTronomers To look aT Looking at Distant Objects Objects look different m as w depending on how they are Cu 0 viewed 3 I Q I We are unable to walk g a 0 around an object which is g millions of lightyears away Goff So we have to try to interpret what we see compare to objects oriented differently 1 Looking at the Dark Sky Galaxies are large collec rions of s rar39s millions and billions of s rar39s The Milky Way is our39 own galaxy There are hundreds of billions of galaxies in The Universe Millions ro hundreds of billions of s rar39s in each galaxy 1 Types of Galaxies iii i 3973 i l r ii ii iii ii ylti ii r r based on shape y39 i yinrt i rotating disk with arms ii oval disk of stars more chaotic motion it Iquotr39iiquotquot Vii wI Ki i nohe of the above I Active Galactic Nuclei Some galaxies have supermassive black holes a r The cen rer39 If ma rer39ial is falling info The black hole enormous amoun rs of energy are released accr39e rion disk I Can shine wi rh a luminosi ry 2 of 1100 million Suns Quasars are a Type of AGN i G Iaxy Collisions 7 7 C fx 7quot 395 x quot 39 i39v i n 73 f quot1 w I m WNW M i 1 x 7 x V WI 1 A you r 39 1 39 quot 139 i7 j4quotquot 1 Orb don39T oc ruolly slam info Think of walking eaCh OTher39 around before a 1 Hit of DEL l fOOtba game n39 lt 39 v r 1 7 if U K quot 2 39 sf USA11 f LHJJ 3 N1A Th 1 g c w E1 r 3 quot 1m Ni V J IV L 1 M Ugo gm f rahxx I w d 39 s ror39 for39mo rion AGNS ue To gr39xovi ry g Looking at the Milky Way Viewed as a br39ighT band of sTar39s across The sky GalacTic cenTer39 a pear39s in The souTher39n EarT of The sky mm The nor39Ther39n emispher39e Much of The Milky Way is blocked by dusT dar39k band Through The middle of The Milky Way BuT we can sTudy iT in longer wavelengThs eg radio waves


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