INTRODUCTORY ASTRONOMY 2
INTRODUCTORY ASTRONOMY 2 ASTR 1020
Popular in Course
Popular in Astronomy
This 96 page Class Notes was uploaded by Stephan Kuvalis on Thursday October 29, 2015. The Class Notes belongs to ASTR 1020 at University of Colorado at Boulder taught by Jack Burns in Fall. Since its upload, it has received 34 views. For similar materials see /class/231949/astr-1020-university-of-colorado-at-boulder in Astronomy at University of Colorado at Boulder.
Reviews for INTRODUCTORY ASTRONOMY 2
Report this Material
What is Karma?
Karma is the currency of StudySoup.
Date Created: 10/29/15
ASTR 1020 Stars amp Galaxies May 2 2008 Final Exam May 5 430 700 pm Chapters 1112 4144 5 13 14 15 16 17 18 19 20 21 22 23 24 Astronomy Picture amp Video of the Day VldED ullhe Hlsmvyul Evemmng 2 Final Exam on May 5 430 pm to 700 pm here Study with a buddy Chapters 1112 4144 5 13 14 15 16 17 18 19 20 21 22 23 24 Review 3 midterm exams notes on class website MasteringAstronomy assignments clicker questions key concepts work sheets from recitat39on Format 40 multiple choice questions 10 true false and s ortanswer questions Also extra credit question Be sure to bring to Exam A number 2 pencil Your CU ID One page front and back of notes for the exam A calculator Review of the Course Four sections 1 Scales matter energy amp light 2 Stars 3 Galaxies 4 Cosmology Co urse Goals To develop a broad view of what we know about the Universe To understand the forces that shape the Universe and its history To help you understand howwe gured out all this ff 1 The Scale of the Universe The Cosmic Calendar mum Atoms nuclei protons amp neutrons e ons Matter amp Energy Different forms of energy kinetic thermal potential radiation light massenergy Energy is always conserved The Electromagnetic Spectrum Padlu lnlrared Mslblellghl ultrayrolet Xrlays Gammarlays r 7 ln order ollncreaslng homered lncreaslng lregoency and DECREASWG Wavelenng Light and Matter Fuurvvays to mahe llght Thermal soectrom Hydrogen Zlccm e s lurlllrle lnclodlng 2 frum later chapters Emlsslon llrles absurptlun too Synchrotron emlsslon o 2 Stars The Sun shmesyylth energy released as hydrogen fuse lrltu hellum Dyerall mslon rate yery stable grayltatlonal m edolllorlo Vlulerlt actlylty on the surface Measuring the Stars Estimating distances via parallax Apparent brightness and distance 9 luminosity Measuring temperatures via color spectral type OBAFGKM Measuring masses via binary stars The HerzsprungRussell Diagram The Main Sequence More massive stars are rarer hotter brighter shorter lived Can estimate ages of star systems from main sequence turnoff 0 Star Birth Low mass stars Stellar Evolution Sequence of expansion and deflation in response to core nuclear burning Red giant planetary nebula white dwarf High Mass Stars Very rapid sequence fusing heavier elements up to iron Supernova explosion Neutron star or black hole remains Neutron stars Black Holes Stellar Graveyard White dwarfs and the possibility of white dwarf supernovae possible pulsars Our home spiral galaxy bulge halo amp disk StarGas Star Cycle Gas dust amp stars A black hole in the galactic center Other Galaxies Galax Types spirals elliplicals irregulars Bulgesspheroids older Disks slar forming slars loday Measuring Distances through the Universe The Expanding Universe Hubble39s Law The dislances belween galaxies are gelling bigger Running lime backwards 9 age of lhe universe Galaxy Evolution Galaxy formalion using presenlday Galaxy inleraclions Aclive and slarbursl galaxies Clicker Questi n Which of the following is NOT an indication of Dark Matter a Flat rotation curves for spiral galaxies b Gravitational lensing in Galaxy Clusters d Con nement of hot X ray gas in clusters of galaxies Clicker Questi n Which ofthe following is NOT an indication of Dark Matter a Flat rotation curves for spiral galaxies b Gravitational lensing in Galaxy Clusters dwarf supernavae gt This is dark energy d Con nement of hot Xray gas in clusters of galaxies 4 Cosmology Rotation curves galaxy clusters 3 ways suggest large amounts of DARK MATTER Probably an unidenti ed subatomic particle WIMP The Fate of the Universe bblE cunstant sets the Expansiun rate fur NOW Dark matter pulls Expansiun curves duvvnvvards e Upwards curve suggests DARK ENERGY pushing against gravityl 39 Evidence for the Big Bang Expanding universe Cosmic microwave background Helium amp Deuterium from the Big Bang Ages of stars I I g 3 a v In ation a Through an ofthis vve Explured tne nature pr We sh tter and Energy tne suurees at all light and warrntn tne urigin uftne Elements ufvve are madEr uur cusrnu histury uurplace rntne universe all not cease from exploration and the end of all our exploring will be to arrive where we started and know the place for the rst time T 8 Eliot You Understood the Universe omstavnek scamp ete ASTR 1020 Stars amp Galaxies April 2 2008 Reading Chapter 21 sections 213 MasteringAstronorny Homework on Galaxies and Hubble s Law is due April 7 Astronomy Picture of the day Weak Lensing Distons the Universe Mkllerm REFSm Avmga Miderm 5mm versus Ammdanm Days a Days In Aucnmnm Today Lookbacktime More on redshifts Cosmological Expansion The evolution of galaxies Lookback time Astronomers can look back into time by observing distant objects ExampleAndromeda is about 2 million light years We see Andromeda as she appeared 2 million years ago not as she is today Measuring distances to far away galaxies is difficult but measuring Doppler shifts velocities is easier from spectra Use Hubble law to estimate distances v H0 x cl napalm brightnu nppml mlgmnu 39m we do tin in mmmnm ml uo39soe Larger redshift what is usually measured larger velocity larger distance larger lookback time So redshift can used used as a time reference that is this happened back at redshi 6quot Cosmological Redshifts 5 De nition of Redshift ii Zredshi quotw a gammy i r a a ubserved Wavelength ves1 wavelength 11 dshi s always nave zgtu redder light has larger Wavelengths Clicker Question We observe a distant galaxy where we see a bright emission line at wavelength 1312 nm a 21 b 21 3 c z2 Observed rest wavelength 1Z 1312nm656nm2 so Redshi Z1 We see this galaxy as it appeared back at redshi 1 quot Redshift also expansion factor 12 alsu measures nevv much universe has Expan Ed As universe Expands Wavelength er light is alsu lengthened 12 distance between alaXlES nevv distance between galaxies then Most distant galaxies nown have redshifts Z 6 Halpha has a wavelength of 12 7 times normal this is a BIG redshift in is now far into These galaxies are very distant Lookback time is large Universe has expanded by a factor of 7 since then NOW redshi 0 12 observed rest wavelengths So Z0 means that the wavelengths are not redshi ed 12 expansion factor The universe is its present size NOW Example a galaxy is observed at a redshift of 1 By the what factor has the universe expanded since the light le that galaxy Expansion factoris 12 2 so the universe has expanded by a factor of 2 since then Note that the galaxies are no longerwhere we see them now but at Z1 were at the exact place for their light to arrive at Earth today Over the largest scales think of the cosmological redshift as an expansion factorthat is related to time since the Big Bang and not as a velocity The Cosmic Horizon What is the biggest redshilt that is possible see How far back in time can we see Redshi in nity 9 the Big Bang Can we look all the way back and see the Big Bang Almostll Z 1000 universe much denser 9so dense it was opaque 100000 yrs 00001 billion years afterthe Big Bang We see an opaque wall of highly redshifted factor of 1000 light all around us Cosmic Microwave Background Lots more on this laterl Galaxiesto z4i Making a spiral galaxy Start with a mostly uniform cloud of hydrogen Gravitational collapse to a protogalactic cloud First stars born in this spheroid spheroid stars are billions of years old 9 fossil record A slight variation Several smaller protogalactic clouds may have merged to form a single large galaxy May explain slight variations in stellar ages in the Milky Way As more material collapses angular momentum spins it into a disk Stars now formed in dense spiral arms disk stars are younger Clicker Question The primary reason that massive Otype tars are not found in the galactic halo is because they are a too massive to be kicked into the halo from the disk so massive that they settle into the thinner disk too shortlived to have persisted from halo formation until today too far away for us to see them 93 amp C Too short lived to be in the halo Halo stars were born billions of years ago the most massive stars don t live nearly that long VWI have disappeared by now after having enriched the protogalaxy gas with heavy elements Making ellipticals For some reason star formation uses up all the gas fast Nothing le to make a disk Now we see a sphere of old stars Or maybe Galaxy collisions des roy i Burst of star formation uses up all he gas Le overs train wreck Ellipticals more men in dense galaxy clusters ASTR 1020 Stars amp Galaxies April 9 2008 Reading Chapter 22 sections 223 MasteringAstronorn y Homework on Dark Matter is due April 14 Meet at Planetarium for next class Last midterm Exam next w Wednesdav April 16 Chapters 193223 Today Gravitational Lenses The Search for Dark Matter Large Scale Structures in the Universe Clicker Question gravitational lens If you measure the redshi s of the red and blue objects you ll nd A The red galaxies have similar redshi s all higher than the blue galaxies B The blue galaxies have the same redshi which is higher than the red galaxies C Red and blue galaxies have similar redshi s B The blue images are a single BACKGROUND galaxy being lensed by the foreground cluster red galaxies The blue galaxy is fartherfrom us and thus will have a higher redshift Gravitational Lenses Dark matter warps space 9 acts like a lens and distorts and magnifies the view of more distant galaxies imagenl real lmagenl galaxy galaxy galaxy Astronomy in the News Larissa Rhodes m almmlly Lenxcd mm ya all new 39 39 Y The Beast 4 or 5 different galaxies Red arc at the bottom z48 How much Dark Matter All cluster methods generally agree About 10 times as much dark matter as normal matter overall in the universe Note that our solar system is NOT typical much more light matter than dark matter here Expected mass of DM inside the Earth s orbit is an immeasurably small fraction ofthe Sun s mass Mass to Light ratio is high in the Milky Way halo but low in the solar system Normal Matter versus Dark Matter Normal matter based on protons and neutrons baryons Normal matter Baryonic Matter ls Dark matter baryonic or something different and new What is dark matter Two avors for Dark Matter 1 MACHOs Massive Compact Halo Objects Stuff we ve studied already very faint things baryonic matter Brown dwarfs black holes black dwarfs etc May be oating through the galaxy halo unnoticed MACHO Searches Use gravitational lensing When a MACHO oats in front of a r suddenly brightens Focusing effect of com act massive object Results 1 WM i a MACHOs are detected But not enough to explain all dark matter 2 WIMPS Weaklylnteracting Massive Particles Nonbaryonic 9 subatomic particle Neutrinos Probably not They move too fast and can39t be collected into stable galaxy halos Other unknown particles Slower particles Cold Dark Matterquot Clicker Questio d on observational evidence is it possible that dark matter doesn t really exist Clicker Question Based on observational evidence is it possible that dark matter doesn t really exist No the evidence is too strong a No the evidence is too strong a b Yes but only ifthere is something wrong b Yes but only if there is something with our understanding of how gravity wrong with our understanding of how works on large scales gravity works on large scales c Yes but only ifall the observations are in c Yes but only ifall the observations are in error error Dark Matter amp the Formation of Gravity puns ructure galaxies and dark matter In the beginning We large structures Very small ripples in density Clusters Gravity pulls together dark matter in slightly denser superclusters regions to form dark halos als39 laments Voids Light matter radiates energy and sinks to the middle to form galaxies Evolution of Galaxy Clusters Real data versus computer simulations ASTR 1020 Stars amp Galaxies April 28 2008 Reading Chapter 13 Extrasolar Planets MasteringAstronorny Homework on The Fate ofthe Universe is due April 30 Final Exam May 5 430 700 pm Chapters 111241445 13 1415163 17 18 19 20 21 22 23 Back to the Moon and Back to Stay ska Plannlarlum Plasanls Till WE iii The New Rockets Ares amp V and the New Spacecraft Orion 2 Site for a unar Base Shackleton M Ml newquot quot 4535 ml wwdtm 2 aquot 3 may Inlvm was mm mama m am u in m h m mumhm mu IM mum Manchu1mm u man mw main um i up n mum I an Iceman h R0 5 Ru 0 Obsuvu 0 or Lunar Sc net 50 mm mm I we up Type II Burst snurce lncmmn Cnmrllex Type III snurce lnczllnn ROLSS Wm produce tne rst ntgn angutarresotutton a at to MHZ ntgn ttrne resotutton trnages of sotarra t erntsstons outereorona ROLSS Wm study now ntgn energy parttetes are generated n e sun Tnts radtatton ts a dangerto future astronauts c m m w CD5 onlzatlon r3 of Galaxleil Clicker Question Which of the following is the correct order of the eras in the history of the universe a Nucleosynthesis GUT Atoms Reionization b GUT Nucleosynthesis Atoms Reionization c Atoms GUT Reionization Nucleosynthesis Clicker Question Which of the following is the correct order of the history of the universe a Nucleosynthesis GUT Atoms Reionization b GUT Nucleosynthesis Atoms Reionization c Atoms GUT Reionization Nucleosynthesis any Mann mm an mophyucm m m Space mg cop Science Inunmz in Baltimore Maryland Science 16 Marc h 2007 The Universe n Transition 39 Recnmhinminn lannnnn yrs To My The Dark Ages einnizzlinn 519 stars 11na yrs W Which kind of object is the best standard candle for measuring the distances to nearby galaxies a A white dwarf star b A Cepheid variable star c A white dwarf supernova Which kind of object is the best standard candle for measuring the distances to nearby galaxies a A white dwarf star b A Cepheid variable star c A white dwarf supernova Which kind of object is the best standard candle for measuring the distances to distant galaxies a A white dwarf star b A Cepheid variable star c A white dwarf supernova Which kind of object is the best standard candle for measuring the distances to distant galaxies a A white dwarf star b A Cepheid variable star c A white dwarf supernova ASTR 1020 Stars amp Galaxies March 5 2008 Reading Chapter 18 section 183 summary of key concepts MasteringAstronomy Homework on Star Death is due March 10 Exam 2 on Friday March 14 Chapters 153192 Meet Friday at Fiske Planetarium for Dr Einstein s Universe Astronomy In the News Varsha smmam ll Chandra Videu The Stellar Graveyard Low mass stars 9 white dwarfs gravity vs electron degeneracy pressure High mass stars 9 neutron stars Gravity vs neutron degeneracy pressure Even more massive cores 9 black holes Gravity wins White Dwarfs For solarmass star a hot core of carbon can also be oxygen for higher mass stars Size Earth Density 1cm3 weighs about 5 tons Cool from whiteblue through red to black Today Neutron Stars Gravity vs Neutron degeneracy pressure Size 10km Crushing gravity at its surface Neutmn staruver ch Supernova remnant 386 AD and pulsar seen in Xray light Pulsars Collapse to a neutron stars increases both rotation and magnetic eld B 9 HQ 3 7 Newly collapsed 39 neutron stars rotate I 100s to 1000s of times per second w Magnetic elds cus energyradiation n alo g magnetIc poles New form oflight synchrotron radiation When the beam sweeps across the Earth we see a pulsar It lFlerEam mg g Gmup Earth lies at the unique intersection of many pulsar beams use these as galactic pointers to our location Pmneev 1 n Spacecva panelr WW 1351 Plum Synchrotron Radiation Fast electrons in strong magnetic elds 9 neutron stars black holes Different shape 39om thermal radiation strongest emission in radio Clicker Question The coolest objects in the galaxy are at about 29 K and the hottest stars are at 29000 K At what wavelengths do synchrotron radiation dominate Wien s law Wavelength 2 900 000 nrnT a less than 01 mm more than 1000 nm b less than 01 mm more than 100 nm 0 less than 1 mm more than 1000 nm 1mm 1m1 nm a Cold Wavelength 290000029 100000 nm 01 mm This is in the far IR near the edge of radio b Hot Wavelength 2900000 29000 100 nm This is in ultraviolet light c So this is answer less than 1mm more than 1000 nm This is the radio part of the spectrum Not matched Scalesl Normal 5 Really stands out in radio and Xray Where there is little thermal radiation Visible light versus X rays show stars versus collapsed objects Neutron Stars black holes Visible light vs Radio Thermal versus Synchrotron Observing Pulsars Jocelyn Bell Cambridge graduate student in 1967 discovered pulsars by accident from an early radio telescope LGM s Pulsar Lighthouses don t actually pulse Must be very compact object to spin so fast Spin slows down gradually thousands of years lrnaa wCTDJ J sec lr ilsec IVOBS 59L Tuugc i yt 4 Neutron Stars in Binary Systems Visible versus Xray 39 gasitrfns r t t I Thermal light from 39 EVI a Iona p0 en la ene stars 9 vusnble and 9 Xray radiation IR emission Synchrotron light from neutron stars 9 X ray and radio XRay Binary system Xray bursters Matter falling through the ning spin isk can spin UP the pulsar When the mass is too great For even neutron degeneracy to hold up supernova core collapses to an infinitely small point 9 Black Hole Next class at Fiske Planetarium on Dr Einstein s Universe ASTR 1020 Stars amp Galaxies March 19 2008 Reading Chapter 20 sections 203 Meet Friday at Fiske Planetarium Hubble s Expanding Universe bring your clicker Astronomy in the News lill Hulley UKS 17 A Universe Full of Galaxies Galaxies are classified into basic types Use both shapes and star properties Sizes range from giants through biggish like the Milky Way through dwarfs Spirals 80 of galaxies Disks spiral arms AND central bulges halos Some have bars across the centers Elliptical 15 of galaxies Round or slightly flattened Very little cold gas no 21cm emission dust or young stars Reddishyellow color old stars red giants red main Dwarf ellipticals Most common type of galaxy Only know nearby ones faint sequence Irregular Where they live Galaxies in Spirals mostly in formation groups 310 Or Transition Often LOTS of star formation galaxies Ellipticals more often in dense clusters of galaxies 100 s 1000 s 39 Why Chapter 21 A dense Galaxy Cluster The Big Picture the universe is filled with a network of galaxies in groups and clusters Mapping the Universe We need Distances to Galaxies So far Parallax New methods standard candles 1 Make some measure of an object which identi es its luminosity 2 Use this luminosity and measure apparent brightness to infer distance to it Start with a cluster Compare with other 1 Main sequence fitting dlstance known via parallax upper clusters lower Which is m ore distant the upper or lower 2 Cepheid Stars Re ion onthe HR Hquot diagram with large bright stars Outer regions are unstable and tend to See Ch pulsating variable stars Star expands and contracts getting Period one whole cycle brighter and fainter Cepheid Stars Period luminosity relationship Overall brighter Cepheids have longer periods 3 i E elephants and 777 77m 7 w 7 hummingbirds Clicker Question Two Cepheid stars Fred and Barney have the same apparent brightness Fred has a period of 5 days and Barney of 1 0 days Which is closer a Fred b Barney Cepheids as Standard Candles A Fred Measure period at variabiiity Fred has a shorter period and so must be me periude less luminous hummingbird Wirms tweiatmm infer the iuminusity Less luminous but the same apparent C mpare With brightness means that Fred is closer to us aware Em and determine distance Today s Class ASTR 1020 Stars amp Galaxies Measuring brightness of the Stars February 6 2008 Measuring apparent MasteringAstronomy Homework on brightness of stars The Sun is due Feb 11 0 Reading Chapter 15 Section 151 Measuring stellar luminosities Magnitudes Fiske Planetarium Show Colorado Skies Celestial Mechanics Thursday Feb 7th at 800 pm A passrve science Stars take millions billions of years to go through their life stages we rarely see a single star change Stars are so small compared to their distance to us that we almost never have the resolution to see their sizes and details directly point sources Observing many different stars lets us figure out the sequence of a single star s life We deduce everything by measuring the amount of light brightness at different wavelengths color spectra Stellar Luminosity 0 Next few lectures focus on how we figure 39 What we measure apparent brightness out the properties of stars how bright it appearsto us here on eart 0 Coming soon how we deduce the ages and life histories of stars 39 Whatwe wanm kmw luminosity how much energy is emitted Joulessec or watts aka absolute luminosity A Big Problem in Astronomy A star ofa given apparent brightness could be EITHER a very luminous star far away OR a lowluminosity star close NEED TO KNOW THE DISTANCE TO THE STAR Lurmhasity Amount of power a em mates energy per second w ts Appsrent brightness ount of smxlxght that Am 6 reaches Eaxrh energy per second peh square meter Clicker Question These two stars have about the same luminosity 39 h one appears brighter A Alpha Centauri B The Sun Clicker Question These two stars have about the same luminosity which one appears brighter A Alpha Centauri B The Sun Inverse square law Luminosity passing through each sphere is the same M The relationship beeheeh eppueht brightness and lumlhoemy depends on distance L Brightness m m ty 47 hence we termine a sage lumlhoemy if we can masuxe its distance and eppexeht brightness Lhmlhoemy 47tdismncezxBnghtness Clicker Question How would the apparent brightness of Alpha Centauri change if it were three times farther away A It would be only 13 as bright B It would be only 16 as bright C It would be only 19 as bright D It would be three times brighter Clicker Question How would the apparent brightness of Alpha Centauri change if it were three times farther away A It would be only 13 as bright B It would be only 16 as bright C It would be only 1I9 as bright D It would be three times brighter Magnitudes all you need to know Dates back from the original Hipparchus 190 BC Convenient only because it can handle huge ranges in brightness factors of 1 0 via logarithms A kind of ranking of a star s brightness Apparent magnitude ZERO is the brightest star in the sky Mag 7 is faintest naked eye can see Mag 30 faintest ever really detected NOTE THE BACKWARDS SCALE Bigger number is fainter How do we measure the distances to astronomical objects We ll keep asking this question again over the semeste Several techniques each valid for different objects at different distances Technique 1 for next class PARALLAX ASTR 1020 Introductory Astronomy 2 Stars amp Galaxies January 23 2008 Professor Jack Burns Newcomers All class info is at website htt solo colora 9 do edu abumsAstrlEIZEISEEIEmdex htm Fiske Planetarium Show Colorado Skies Observational Astronomy Thursday Jan 24 at 8 00 pm Planetarium To receive extra credit for attending a Fiske Planetarium show1 point you will need to sign your name on a sheet at the s o Either the tickettaker or the person doing the show will provide you with access to the shee Fiske shows are 39ee each Thursday night 2 Homework Reading Chapter 5 sections 51 52 summary of key concepts MasteringAstronomy Tutorials amp Exercises plete b Need volunteers forAstronomy in the News on Fridays please Email me Astronomy Video of the Day Today s Class Energy and Matter Types ofenergy Conservation of Energy Gravity Matter atoms molecules I Clicker Question from Reading Which of the following energy types is also a form of kinetic energy choose one A Emc2 BThermal heat energy C gravitational potential energy D Sunlight Clicker Question from Reading Types Ofenergy Which ofthe following energy types is also a 1 K39netlc Energy form of kinetic energy choose one Movement energy greater for larger A Emcz masses faster movement B Thermal heat energy 0 gravitational potential energy Examples rolling falling zooming D Sunlight swinging etc Thermal energy measured with an 12quot Thermal energy absolute temperature scale The them energy of T degrees Celsius T Fahrenheit 32 things 1 8 T in degrees Kelvinquot Celsius 27315 degrees A form of kinetic energy M m39 WC 7 m e 51 ut with random motion Increasing mt W 39F vw thermal energy causes atoms to move faster v e 7 4mm 5 mm cm mam Examples 2 Potential energy HDtplZZa Elven Energy which has the potential to become ASDF 45m 32 l E 232 C EDS K kinetlc thermal or radlative energy Think of it as stored energy R m p 7332 E 21 c 234 KN gnu K Examples rock on a high ledge remember thls number gravitational potential ashlight batte Surface ufthe Sun suuu K electric potential lrlterstellargas lEI K candy bar chemical potential Absulute zeru nu thermal energy lrr matter all atumle rubber band stretched and held mutlurl stups El K Mass energy a special form of potential energy under special Situations to energy Em m mass convened to energy c speed or light Since c is iarge this means that 3 energy atom bomb 3 Radiative energy All types of light Sunlight lamplight Radio waves Xrays 9 MUCH more on this later Conservation of Energy AN IMPORTANT CONCEPT Energy can be converted from one type of energy to another but never created or Many actions in the universe represent the conversion of one orm 0 energy to another bering conservation of energy is key to understanding how everything works What are Newton s three laws of motion Newton s rst law of motion An ob39ect moves at constant velocity unless a net force acts to change its speed or direction Newton s second law of motion Force mass gtlt acceleration Newton s third law of motion For every force there is always an equal and opposite reaction force What determines the strength of gravr The Universal Law of Gravitation ery mass attracts every other mass Attraction is directly proportional to the product oftheirm sses Attraction is inversely proportional to the square ofthe distance between their centers N 0 Mt M1 M2 2 d 2 Clicker Question If Earth were twice as far from the Sun the force ofgravity attracting Earth to the Sun would be a Twice as strong b Halfas strong c Onequarter as strong Clicker Question If Earth were twice as far 39om the Sun the force of gravity attracting Earth to the Sun would be a Twice as strong b Halfas strong 1 Onequarter as strong Astronomy Picture of the Day ASTR 1020 Stars amp Galaxies March 17 2008 Reading Chapter 20 sections 201 202 MasteringAstronomy Homework on The Milky Way is due March 19th Volunteer for Astronomy in the News sign up for 880 extracredit observing Meet Friday at Fiske Planetarium Hearlng un NASA S smence Prugrams March 132mm Spiral patterns in galaxies are ve common Why don t 9 wind up Material is pulled Splral ArmS a little forward or a backwards towards the high Density wavesquot stars density regions move in and out of denser regions Note how this More like ripples in a pond creates a splral th n arms ofa pinwheel pattern In dense regions star formation is more intense so arms are brighter How did it get started The Galactic Center Constellation Sagittarius Possibly a bumppull from the gravity of another galaxy Nothing very interesting there IR or Radio Clicker Question We want to map out the structure of the core of the Milky Way 39 Dfust 050th oulr Vision 0 muc 0 egaaxyin What wavelength should we be usmg visible and Wlight and why X rays only highlight the hottest and weirdest a IR or radio places b visible light 0 XrayS IR and radio light pass through unaffected show dust stars gas Radio observations Sagittarius A Name 445 BED 5 Agni 2mm AM u m hm Animation of Star Motions in the Milky Wa Center Adaptive optics to 39 separate star images Observing over several years In 39ared wavelengths to see through dust Some ofthe mass is stars the rest is in a 34 million solar mass black hole mgr w quotw 5m x mdgnll n vmy mxlvu mm m n Imnll wequot 3 n E L J i l y m amlulvulmlun mm 5 s 2 39 n 2a 395 my mum hum w r mumm Clicker Question A 3 million solar mass black hole represents a 999 ofthe mass ofthe Milky Way b 1 ofthe mass of the Milky Way c less than 11000m the mass of Milky Way Hint How many stars are in the Milky Way check last class notes Dark matter outweighs this by about a factor of 10 C Less then 1I1000th Number of stars 100 billion 10M Total mass 10 x10M 1012 a trillion 3 million solar masses I1012 solar masses 10395 or 1100000 Tiny 39action ofthe galaxy but still remarkable because it s in such a tiny space Astronomy ln the News CUVEOULDER SPACE Introductory Asfronomy 2 SClENTlSTS READY FOR MESSENGER MlSSlON tars amp Galaxies BY OF M ERCURY January 25 2008 Professor Jack Bums ewcomers All class info is at website httg sulu colorado edu aburnsAstrlEIZEISQEIEmdex htm m mm mmquot ammzssmzn mm We M5 mm mm mm mmth with m Mmmmm ms mm quotW Homework Today s Class Reading Chapter 5 sections 53 55 summa cepts Chapter 5 Matter and Light ry of key con MasteringAstronomy Tutorials amp Exercises Atoms and Molecules c es ofthe Universe complete by L ht W d Jan 28 For calculation problems use at Plg I aves an least 3 significant digits example 134 or arm es 134 Correct answer has to be within 2 39 The EleCtmmagnetlc Clicker points start on Monday SPSCtrum Matter a Material World Atom Atoms nucleus made of protons and neutrons nucleus electron A surrounding cloud made of electrons please try 7 to get rid ofthe solar systemquot vision of atoms Electrons are held onto the atom by electric force Electrons have negative electric charge protons protons are positive Neutrons are neutral 5 neutrons Hydrogen simplest and most common atomic number 1 atomic mass number 1 Helium atomic number 2 atomic mass number 4 x Periodic Table of the Elements What if an electron is missing ion r atomic number protons atomic number 2 1 atomic mass no protons neutrorLs atomic mass number 4 He m What if two or more atoms combine orm a particle molecule 8 H20 water Wave Nature of Light Speed ufhgbt e auu uuu kmsec Waveiengtb er hgbt is be quot distance frum crest El crest A iambda measured 3 E elt Particle Nature of Light Light can also be thought of as a particle 9 photon A photon is a massless particle of electromagnetic radiation energy N Dual nature of light N Waveparticle dualityquot Seen in other particles eg electrons as well u Photons can have any energy from tiny 39gant39c The greater the energy of the photon E the higherthe 39equency smaller the wavelength Ef E1l The Electromagnetic spectrum rm 391an mumtam mmKl to n mu 4 Vzmml ays lkumby lhnlzt tan mu Moray lduhmwnll W m4 as mm mm Spectra and spectral analysis A spectrum snuvvs the lntEnSlty er llgntversus wavelengthhequehey OR energy Can be created by passlng hghtthraugh a prlsrn ur ether uptlcs Spectral ahalysrs uses What We knuvvabuut nuvvllgnt Note valnbawls ahw aeeurate tar Visible ham w aha W are invisible aha have ha calml SPEC rum WE can tell Note dark aahaswhere ham lsabsem aha areas Wneve ham is more intense u m Clicker Question Frurn the spectrum shaWh here E None ofthe above The color in visible light would be yelloworange with some invis39 emission in the infrared The ne features would not be discernable to our eyes E m mama Objects can lookvery different depending on the wavelength of light you are detecting gt39L 1 n t realm Sun as seen n visible UV X ray and radio light Emission from Atoms IF electrons are in a high ener y s according energy Ener is conserved Each atom has a different set of energy levels 9 different emissionabsorption spectrum Examples mercury sodium neon hydrogen mercur Demo diffraction grating spectroscopes mm Most common visible light emission line I 39 HydrugenAlpha n tn n2 energylump atBEES nrn The universe is rnustly pinkll ASTR 1020 Stars amp Galaxies April 18 2008 Reading Chapter 23 section 231232 Extra credit Fiske Planetarium shows every Thursday and SBO observing Astronomy In the News nil omwulumm me quotmy Piolecmc m he one mnmn cums At least too u as cxoss yrnlstnhuil 2 Today Chapter 22 Section 4 Dark Matter Dark Energy and the fate ofthe Universe Preview of Chapter 23 The Creation of the Universe the creation of all matter light and energy Dark Matter and the Fate of the Universe Expansion begins with the Big Bang everal different models for Past and Future Iverg anquotan Wee glllxles u v llmelhtlltunaalyuul lulum What is the fate of the Universe Recollapse crushing heat destruction of all matter rebirth Eternal expansion cold galaxies dimming star formation slowing everything winds up as a brown dwarf black dwarf neutron star or black hole Some say the world will end in re Some say with ice From what I ve tasted of desire I hold with those who favor re But if I had to perish twice Ithink I know enough of hate To say that for destruction ice Is also great And would suf ce Robert Frost clicker QuestionWhich universe predicts the largest age for the universe today a Recollapsing if b Critical 39 c Coasting g V i 1 2 g a Ignore accelerating for now C Coasting Age of the universe is 5 2 how far to the left the distance between galaxies 0 Which is it Is there enough dark matterto recollapse the universe Baryonic matter only a few percent of critical density Dark matter only about 25 of what is needed Universe is in between the coasting and critical models The Universe will expand forever Clicker Question If there was really ZERO dark matter in the universe which model would be the closest to reality a Coastin b Critical c Recollapsing mf wmmmwwmm umuululonnlvnvi rm Baryonic matter is lt 5 percent of the critical density Closest model would be the Coasting Model no deceleration from gravity A New Twist for the 21st Century White dwarf supernovae standard candles at z1 Explosions bright enough to see very far away Z1 means about halfway down from the NOW 2 7 level a expansion factor 1Z 2 1 Redshifts of the supernova plot their vertical position e mm Mm Their brightness plots their horizontal position Dimmer more distant longer ago Supernovae are DIMMER 3 m y than expected x kw for a coasting niv se Universe is accelerating How can the universe be accelerating A force that counteracts gravity Dark energy outweighs every other form of massenergy Truly an unknown force in all of physics Read Einsteins Biggest Blunder p 679 Accelerating model universe Longest time since Big Bang 14 billion years Oldest stars are about 13 billion years 0 0 er models fall short Universe will expand i M forever still Mll there be more surprises to come Summary Contents of Universe Normal Matter 44 Normal Matter inside stars 06 Normal Matter outside stars 38 Dark Matter 25 Dark Energy 71 Chapter 23 In the VERY Beginning Hot stuff Everymrng m the Unwerse M was nutteratearher u r Urnes and men eneree as w rt Expanded 5 The temperature at the Earhest urnes Was mere than the Energy WE create rrr pamde aeeraturs Cesmeregy at the Earhest Urnes rs expreree vra pamde physresr Matter and Energy Emc2 murmurquot Emma IV pm uem Matter and energy are quot19 Simer Ciquot wryquotmm mm Immnlmn transform from one to Enamel Fnaunmmlmon meow may we Matter antimaner e 6 9 photons Ikc wn ASTR 1020 Stars 81 Galaxies March 3 2008 Reading Chapter 18 section 182 summary of key conce ts MasteringAstronomy Homework on Star Death is due March 1 quot39 Exam 1 fusion question Meet Friday at Fiske Planetarium for Dr Einstein s Universequot Quick Clicker Surve What do like best about the class so far a Lectures including demos planetarium b Clicker questions to stimulate discussion c MasteringAstronomy Homework d Astronomy in the News e Recitations amp labs Quick Clicker Surve What do like least about the class so far a Lectures including demos planetarium b Clicker questions to stimulate discussion c MasteringAstronomy Homework d Astronomy in the News e Recitations amp labs How would you rate the class so far a Excellent b Very good c About average for similar large classes d Poor Astronomy Picture ofthe Day rwaueiunar chases 1mm main man Last Time Stellar Evolution Low mass stars 9 planetary nebulae and white dwars High mass stars 9 supemovae and neutron starsblack holes Su pernovae Exploding remnant of a massive star disperses and spreads heavy element through the galaxy lhe claw aka Messievl mam an July at mama viable m the daylimei The Stellar Graveyard Low mass stars 9 white dwarfs gravity vs electron degeneracy pressure High mass stars 9 neutron stars Gravity vs neutron degeneracy pressure Even more massive cores 9 black holes Gravity wins Today White Dwarfs For solarmass star a hot core of carbon can also be oxygen for higher mass stars Size Earth Density 1 cm3 weighs about 5 tons Cool from whiteblue through red to black Clicker Question Imagine two star Hint what mass stars clusters one 10 billion create white dwarfs more likely to have a lot of white dwarfs a the old one b the young one c can39t tell Clicker Question Imagine two star clusters one 10 billion years old and one very young Which is more likely to have a lot of white dwarfs the old one the young one c can39t tell 52 mcm ma 1 mm y will Old gIObUIarngtES have Whlte White Dwarfs in Binary Systems accretion disk Inner parts become VERY hot glow in UV X rays Novae not Supernovae Gas falls onto the white dwarf heats and fuses for while Star becomes much brighter 9 nova new star Dimmer than supernova White Dwarf Supernovae White Dwarf Supernovae 39 If white dwarf accretes mass from binary nion so it is gt14 solar masses it will collapse and the star heats to burn carbon If enough mass is accreted electron degeneracy is overcome Limit 14 Solar masses Carbon bombquot 9 entire star explodes White dwarflimit Dr Chandrasekar says Chandrasekar Limit P0 Vljo larwmeizergore We Nothing remains or you Wlll collapsel Compare the 2 types of Supernovae White dwarf binary systems only Not much hydrogen Occurs in older star populations Nothing le inside Massive stars Lots ofhydrogen Found in young starformation regions Make neutron stars or black holes We ll Fe looking at these again as distance measurement too s Clicker Question What is the ultimate fate of an isolated White Dwarf It will cool down to become a cold black dwarf As gravity overwhelms degeneracy pressure it will explode as a nova As gravity overwhelms degeneracy pressure it will explode as a supernova Degeneracy pressure will eventually overwhelm gravity and white dwarf will evaporate 383 Clicker Question What is the ultimate fate of an isolated White Dwarf 8 It will cool down to become a cold black dwarf 8 As gravity overwhelms degeneracy pressure it will explode as a nova As gravity overwhelms degeneracy pressure it will explode as a supernova Degeneracy pressure will eventually overwhelm gravity and white dwarf will evaporate 3 ASTR 1020 Stars 8t Galaxies February 1 2008 MasteringAstronomy Homework on Light amp Spectroscopy is due Feb 4 Reading Chapter 14 section 143 Astronomy in the News R yanMallln Today s Class Energy generation in the Sun Protonproton chain Sun39s ener bud et Mysterious neutrinos quotVisible surfacequot of the Sun photosphere T only 5800 K Photons free to y seen a Ea 8 min Thermal spectrum T 5800 K plus absor tion from cooler gasses just on top Magnetic Fields in the Sun Magnetic elds entrain gas in hu e bubbling loops Cooler areas at iflofr39 cause dark sunspotsquot Outer regiuns are nutter cnrurnuspnere T itinuu K Hydrugen alpha Emlsslun rrurn tnin gas plnkl Heated by energy tWisting and spilling aruund rnagnetie rielg llrlEs7 Corona outermost parts T 1 million K gtXrays Reading Clicker Question Imagine that the Sun s energy generation rate fusion rate suddenly increases by a factor of 10 What will happen A The Sun will increase in brightness by a factor of 10 after 1 million years the Earth s climate will start to heat and after another 2000 years all life will cease B The core of the Sun will quickly expand and cool slowing the fusion rate to its previous level C The core of the Sun will heat up causing a runaway reaction and catastrophic explosion 8 Reading Clicker Question Imagine that the Sun s energy generation rate fusion rate suddenly increases by a factor of 10 What will happen 23 The Sun will increase in brightness by a factor of 10 after 1 million years the Earth s climate will start to heat and after another 2000 years all life will cease B The core of the Sun will quickly expand and cool slowing the fusion rate to its previous level C The core of the Sun will heat up causing a runaway reaction and catastrophic explosion 9 The Sun Where does all that energy come from Nuclear FUSION not FISSION Hydrogen Helium fission fusion Itquot 51va i unnulivwv Where hydrogen is built into helium Hydrogen nucleus 1 proton Helium 2 protons 2 neutrons Fusion occurs via the ProtonProton Chain 4 protons 4 hydrogens 1 helium PLUS Energy Protonproton Chain TWe prutuns uHrde at hrgh speeds NurrnaHy ereeme reree Weurd keep them apart me usrtrve charges reper xtrernet mperatures mean theyhave enuugh energy tn Dyercume thrs Once very ctuse the nudear STRONG FORCE brnds the pameres tugether Once the nuclei are crushed togeth P P 9 P N positron neutrino P N deuterium an isotope of hydrogen Positron is antielectronquot Wh with a normal electron its mas en it collides s is converted to energy gammaraysvia E mc2 Neutrino gets away unharmed Multiple steps in the process saw 5151 2 Step 3 Key t a n M pm a a mum 9mm 3 43 f vmw amquot 39mm w mummy 39 J g 60 mm avg 0 a 3 av a 9 r A 5 a Input 6 protons Output1 helium 2 protons 2 positrons 9 gamma rays 2 neutrinos more gamma rays 4 hydrogens 9 1 helium 2 neutrinos plus 7 clamma ravs enerav Gammarays work their way outwards cool and become Sunlight Neutrinos don39t interact Sun s energy Energy budget Helium has atomic mass 397 times that of hydrogen NOT exactly 4 times Tiny amount of the protons mass is lost to energy via E mc2 Rates are fast enough that 4 tons ofmass are converted each second The Solar Thermostat Why doesn39t the Sun go into a runaway reac ion Fusion rate is VERY sensitive to temperature 9 tight feedback loop lf energy generation fusion rate speeds up 1 Pressure in core will increase lifting the gas against gr vity 2 Gravitational energy is created from thermal ools 3 Energy generation fusion rate slows down 2n If energy generation drops Core pressure drops Solar core starts to collapse Temperature rises Fusion rates go up again But Sun is remarkably stable Small 30 increase in fusion rate over billions ofyears Those Mysterious Neutrinos With very small masses travel close to speed of light Don39t interact with other matter requires a lead wall 1 lightyear thick to stop a neutrino Fewer at nIght Lots ofthem 103B neutrinossec from the Sun 1015 coming through YOU each second Clicker Question Do you think neutrinos flowing through our bodies are a cause of cancer or other damage A Yes BNo B Neutrinos don t deposit any energy in our bodies they simply don t do anything Today Dr Einstein s Universe ASTR 1020 Stars amp Galaxies March 7 2008 Einstein comes to MasteringAstronomy Homework on Amenca In 1933 Star Death is due Mar 10 39 The General Theory of Relatrvrty and eadmg Chapter 19 sectrons 191 Gravity 192 Black holes amp worm Exam 2 next Friday March 14quot 110195 Chapters 53 7 192 Einstein The man and the politicran Einstein in America Spacetime Aphenomenon I I I Physicist as Rock I I SIpecral relatrvrty showed that space and Star I t1me are not absolute quot Instead they are inextricably linked in a fourdimensional combination called spacetime At Hop House Grandcanyonm 1931 Wu w Key Ideas of General Relativity Heavier weights cause a greater I I I I I distortion orthe rubbsrsheet 39 Gravrty ar1ses from d1stortrons of spacetrme Time runs slowly in gravitational fields Black holes can exist in spacetime 10 kg The universe may have no boundaries and no center but may still have finite volumg I Rapid changes in the motion of large 39 masses can cause gravitational waves A Matter distorts spacetime in a manner analogous to how heavy weights distort a rubber sheet What is curved spacetime Great circle is shortest dis etwe a lquot v Hm mu 3 E w Circumference of circle is lt 2m Mass ofSun curves spacetime 7 Freefalling objects near Sun follow curved paths 7 Circles near Sun have circumference lt 27 Clicker Question According to general relativity the presence of matter curves spacetime That means a planet in our solar sy stem a Feels a force of gravity coming from the sun b Moves a ifthere was a force coming from the sun c Experiences free fall or free movement by moving in a curved orbit d None of the above Clicker Question According to general relativity the presence of matter curv s spacetime That means a planet in our solar system a Feels a force of gravity coming from the sun b Moves a ifthere was a force coming from the sun c Experiences free fall or free movement by moving in a curved orbit d None of the above e b and c Curvature near Black Hole event mm mm MIG Continued shrinkage of Sun would eventually make curvature so great that u would be like a bottomless pit in spacetime ablack hale Shortcut Through Spacetime to iirsi aro iiynsrsnacr mo Some mathematical solutions omie equations of general relativity allow for shortcuts called Wurmhules that are tunnels through hyperspacz Are Wormholes Really Possible I Wormholes are not explicitly prohibited by known laws of physics but there is no known Way to make one I lfWormholes exist then they can be used 1 for time trave I Time travel leads to paradoxes that some scientists believe should rule out the a possibility of Wormholes Einstein The man amp husband Einstein s Rules for Milevz in 1914 You will stop talking to me in request It You will notbellttle me in 1d L Ont ofthe chi reri Albert Ya Mlleva 1905 I Emc2 is the basis behind the nuclear bomb I Einstein Wrote to Weapon was possible with Leo Szllard 1946 ASTR 1020 Star s amp Galaxies April 21 2008 Reading Chapter 23 sections 232233 MasteringAstronomy Homework on The Fate of the Universe is due April 30 2 more extra credit opportunities at Fiske Planetarium this week and next Astonom ictur of te Da ie 2543 rna ndnning enieken Nehula ereeii a edE rigni Steve eimn Explanation eiieninetdie mind in and mind the Warm drain 2 till i t t a MA i a Last Lecture Chapter 22 Section 4 Dark Matter and the fate ofthe Universe Today Chapter 23 The Creation ofthe Universe the creation of all matter light and energy Important Diagram Average distanee between galaxies 1 Egtltpansiunfatur t lz now is fixed in tirne ZZEI Hubble unstantNOW sets it a i tne sibpe ufthe iine huvv is 1391quot quot39 39 quotquot Wquot fast the universe is Expanding new big me when em sm zm nny 4 Chapter 23 In the VERY Beginning Hot stuff Everything in tne Universe Was hatter at Earlier times and tnen ebbied as it Expanded Tne temperature at tne Earliest tirnes Was rneire tnan tne Energy WE create in particle aeeeieratbrs Cusmulugy at tne eariiest tirnes is Explured Via partieie physicsl Emc2 Matter and energy are l the same can transform from one to another Matter antimatter 6 9 photons Matter and Energy Pnlrde mquot ummumm e m The Planck Era Before the lirst10quot3 seconds Four Fundamental forces gravity electroma ne39s weak nuclear work as one force No complete theory to describe how this works mediates nuclear reactions and strong nuclear holds atomic nucleus together forces are united Clicker Question Which ofthe four forces keeps you from sinking to the center ofthe Earth A Gravity B Electromagnetism C Strong Force D Weak Force Clicker Question Which ofthe four forces keeps you from sinking to rlh the center ofthe Ea A Gravity B Electromagnetism C Strong Force D Weak Force The Grand Uni ed Theory Era GUT Era Uptu iEIJEsEc Temperatures higherthan quot e n be reated in pam a aeeeier atdrs eie Fundamental tdrees beedrne se univer distinct as tne eddis N F LATIO N s rung ruree be rnes drstrnet a huge amuunt ur Energy is release Universe iNFLATES aturnic 5 e quot ndeieds size becumEs suiar E system size Expands by a factur err 1 mm in in 36 see but DOES NOT COOL Weird but LOTS ufevidence fur iNFLATiON Major Events 39quotquot39 5123 Wm m 74quotquot I 52 396 m hum wquot uncnd Elnmwuk a ma mu 1 w m glam quotmquot mamaquot Mm mum WWI mgmmpflg lemmas muggy 51ng a mm Wesiav The Particle Era Universe still hot 1015 to 1012 K Particles now exist electrons protons antiprotons anti electrons neutrinos etc Particle soup Particles and photonsenergy created and annihilated Matter and Antimatter Protons slightly outnumberantiprotons V 7 J 39 9 At the end ofthe Particle W Iquot Era universe contains some matter Universe today 1 billion h gtto 1 aiiwmw photons lig t lettover proton matter Clicker Question What happens when a proton collides with an antiproton a They repel each other b They fuse together 0 They convert into two photons d They convert into neutrinos Clicker Question What happens when a proton collides with an antiproton a They repel each other b They fuse together c They convert into two photons d They convert into neutrinos rm Sine Maior sums Big Bang Sincn Big Bang m chum m mm m mm Varm g 1139 W6 5quotquot hum ur Eu mm an arm mum Wm mgwmji mmer W4 owgm 0 Milanquot Weer Era of Nucleosynthesis fusion Matter particles are frozen outquot no longer spontaneously generated to 39om ons 5139 J A m Temperatures hot 1 enough to fuse protons hydrogen nuclei to helium nuclei 0001 sec to about 3 minutes afterthe Big Bang Fusion ends because density drops about 25 helium traces of Lithium deuterium Amounts seen throughout the universe today with slight enhancements of heavy elements via fusion in stars Next Two Classes The Rest of History More on Inflation Did the Big Bang Really Happen Astronomy In the News ASTR 1020 Stars amp Galaxies February 8 2008 0 MasteringAstronomy Homework on The Sun is due Feb 11 0 Reading Chapter 15 Section 151 LindeyMaza 1 2 How do we measure the distances Parallax to astronomical objects We ll keep asking this question again over the Measure the apparent semester movement of stars over a year Several techniques each valid for different Movement is caused by objects at different distances Earth s movement around the Sun We need distances to determine luminosities of stars Closer objects will move more than farther objects Technique 1 PARALLAX Class demos Parallax Parallactic angle Your nose Is the Sun HALF of the change in angular position over 6 months Your left eye is the Earth in January Your right eye is the Earth in June I I Watch the ap arent motion of your thumb agalnst a distant reference Larger for Closer ObleCts 6 Smaller for farther objects Movie Which move more closer or farther objects menses Parallax formula Evelvduly w m DIstance parsecs sea s 1 parallactic angle arcsecond Parsec a unil of distance invented just for this method of distance measu ement 1 parsec 1 pc 326 light years Remember 1 arcsecond 13600 degree Ju lv Jammy 7 How do we measure mnces tn mm Clicker Question The biggest ground Parallax and Distance about 005 arcseconds Howfarawa c p pawn angle they map the positions of stars via parallax d in parsccs c a 2 pc 65 light years 7 p in arcseconds 20 pc 65 light years 200 pc 650 light years 85 dinlightycars 325 gtlt p m arcseconds v a Best parallax measurer Hipparcos satellite 19891993 Space measurements nut B arrecteu by atrnusphere maximum distance is set by the accuracy ou can measure positions Measurementmade marrytlrnes urrtll accurate tn u EIEIl arcsec 933nm Distance pc 1 005 arcsec 20 pc WW2 65 ly 1DEI EIEIEI stars mappeu 2 5 rnlllluntu sllghtly lesser accuracy Centerofthe Milky Way is about 28000 light years away Parallax works only fornearb neighborhood We39ll expand to other methods for more distant objects Let s remember that Luminosity Amount Dfpuwex a stat udntes enexgy pexsecund Wm Appuenrbn39ghmas aunt ufsuxhght rim ah Am teaches En 13y pet second pet squat metex Brad and Angelina are two stars that have the same apparent brightness Brad has a larger parallactic angle than Angelina Which star is more luminous a Brad b Angelina c Not enough information Can t tell Brad has a larger parallactic angle Thus he is closerto us They both have the same APPARENT brightness but Brad is closer B Angelina must be more luminous Astronomer s Toolbox What do we know how to do now Measure distance parallax good to nearby stars but not beyond Measure absolute luminosity ure a parent brightness and 39 ity meas p distance infer luminos N ext temperature ASTR 1020 Stars amp Galaxies February 15 2008 MasteringAstronorny Homework on The Properties of Stars is due Feb 18 Reading Chapter 15 section 152 Meet at Fiske Planetarium for class on Feb 15 Exam 1 Wednesday Feb 20 Chapters 1 4 5 14 15 How Q we get a good picture of what our Milky Way galaxy looks like Use infrared or microwaves to penetrate the dust Use radio telescopes to see where clouds of hydrogen gas are Take photos from both the top and side to get a good view All of the above 1 and 2 How Q we get a good picture of what our Milky Way galaxy looks like Use infrared or microwaves to penetrate the dust Use radio telescopes to see where clouds of hydrogen gas are Take photos from both the top and side to get a good view All of the above 1 and 2 ASTR 1020 Stars 81 Galaxies February 29 2008 Reading Chapter 18 section 181 in textbook summary of key concepts MasteringAstronomy Homework on Stellar Evolution is due March 339 Astronomy in the News gtltu n2 Gildelamadnd High Mass Star Core structure keeps on building successive shells Lesser elements on the outside heavier ones on the inside The core ofa high ass star accumulates iron as the layers above it burn Degeneracy pressure s of iron gets too heavy in E Equot a z E E m 3 m Clicker Question Basketball amp o What do you think will happen a The two balls will bounce up together The little ball will bounce higher than the basketball S 8 Nothing interesting the rst time he ll have to do this three or fourtimes to get it to work Supernova The lightweight atmosphere impacts on the heavy core and is bounced offin a huge explosion Huge energy release 39om neutrinos Exploding remnant of a massive star VY element through the galaxy Inside is a neutron star a remnant core of pure neutrons Supernovae The crew aka Messievi MM ntt Juiv n iu r Vishie m the dayhmer F39Etrugiyph rrdrh Chaed Cahydh Current euhnguratmh reiative El the NEW rnuun fur the Crab Supernuvae Yuu eah check this uh yuur SkyGazer pianetarium sdrtware Shuuid ahd mustiy DO fuiiuvv the p reactiuns Heavier Ei hehurh huei Creation of the Elements atterh uf fusruh erhehts are made during the Expiusiun as er are siarnrned intu heavier EiEmEnts This is Deep AH heavy EiErnEnts are ereated and dispersed thruugh the gaiaxy by stars Withuut supernuvaey hdthrhg heavierthan carbun WE ARE STAR STUFF Our aturns were uh e parts at stars that died rhdre than 4 a biiiiun years agdwhdse remains were swept up mm the suiar system when the Sun rdrrhed Abuuti pereehtury per gaiaxynune inMiiky Way since iBEIA Brightexpiusiunvisibie fur Weeksmunthsr sdrhe Visibie in daytimei mnantvisibie fur was at thdusahds at years as huge bubbies and veiis Supernovae in Other Galaxies Brightenuugh td be seen as a sudden brightpuint in uthergaiaxies Scares err amateur and pm astrurrurhers rhurhtur nearby gaiaxies nightiy td catch them per mm years per gaiaxy means that munituring mu gaiaxies Wiii getyuu isupernuva peryear SN 1987 A nearest one since Possible neutrino burst SIX extra neutrinos were detected when SN1987A went off Exploded in Large Magellanic Cloud companion dwarf Nwlrino galaxy to Milky Way 50 event 3 m E Seen on I 20 m southern hemisphere s g u Ll 39A Relltl Mime SN 1987 A Precursor massive blue tar l Ring structure illuminated remnants of an earlier stellar Wind E re now starting to hit this region brightening Double ring traced by energyjet from unseen 39 Clicker Question Binary Systems The Algol Paradox Algol is a binary system consisting of a 37 solar a Binary stars can mass main sequence star and a 08 solar have different masses mass red giant Why is this strange but usuall ARE formed at the same time The more a A 37 star should have become a red giant before a 08 solar mass star mass39ve Star ShOUId have had a shorter b Binary stars usually have the same mass main sequence c 08 solar mass stars usually never become red fe me giants What probably happened The D 8 mar mass star uhee Was mere masswe A n became a red g ant usweueu and puured materwa DMD KS Bumpamun The red gwant s NEW has 15 masswe than eumpahmh Future when the Either stargues red want 1 may Mma a hestm chaase m puur gas back 7 mpanmnswsgh asthevwmav Wee ASTR 1020 Astronomy Introductory Astronomy 2 P39m refll e Day Star s amp Galaxies January 16 2008 Professor Jack Burns Newcomers All class info is at website II Iulmeolondoadul bumsIAIMOIOS EOIIinIIOxIIIIIII Notes from last class are now posted on the class quotWWW 93 website Cred J Hester llnzona sr metal as NASA MasteringAstron om y H omework Reading All homework will be assigned via the Chamw y urn a fKey Canceptsp 21722 onllne 5y5lem Masrermg qsrmnom 39 Intro to MasteringAstronomy complete by Jan Stay up with class assignments in a1kocaleggg g gsgimmm com gMww g y conluncnon Wllh the readlng39 Your grade will be based on completion ofthe The course ID for Astr 1020 In tutorial and exercises MasteringAstronomy is ASTR10205P03 Grades are tracked automatically online Nothin to hand in Stag this exercise now in case oftechnical ro ems Registeryourclickers Today s Class Brief Tour of the Free Planetanum Show Universe Sizes and Scales 39 Colorado Skies Messenger 6 Mercury with Ms Addie Dove hursday January 17 at 800 pm Reading Chapter 1 V Fiske plane arium Sections11 and 12 1 extra credit bonus point on nal grade when you attend a showthis semester be sure to sign 39 Scales In Space sheet when u leave What we ll be Studying Sizes and scales What are they Review of Gravity amp Light How do we use them to understand sizes masses an composition of stars amp axies The Sun Stars of every size and color Star death white dwarfs neutron stars and black holes Our Galaxy The Milky Way Exploring a universe of galaxies Galaxy Evolution amp Central Engines Navigating the Universe The 3399 Bang Sizes and Scales I don39t deal E retend to understand the Universe It39s a great igger thanl amquot Thomas Carlyle 17951881 7 Our Cosmic Address Eanh SunSolar System Milky Way Galaxy Local Group Local Supercluster Scale models of the Universe Scale Sun as a grapefruit 1 10000000000000 Earth pin 15 meters from Sun Mars pin 23 meters Jupiter marble 78 meters Pluto tiny grain 1 mile away See model near the Planetarium On this scale the nearest stars would be a system formed by a cantaloupe a small apple and a kiwi fruit located in Newfoundland Canada There is essentially nothing in between New Scale for the Galaxy Stars are microscopic located 2mm apart Mil Way galaxy is 22 meters in diameter contains 10000000000039s 10039s of billions of stars Galaxies are 10 inch Milky Wa and Galaxy groups and Yet Another Scale for Everything Else paper pla es nearest nei hbor Andromeda are 5 meters clusters contain 1039s to 100039s ofgalaxies 39 Superclusters 50 meters across size of buildings in our scale model are the largest structures we see ble sIze of Bou er in this image Each dutls an Entire galaxy 25 This is big stuff how to grasp astronomical numbers Powers of 10 count the number ofzeros behind the digit review Appendix C in text 1000 1 thousand 103 1000000 1 million 106 1000000000 1 billion 10a 10000000000000000000000 1022 approximately the number of stars in the servable universe moret an the grains of sand on all the beaches on Ea h n Astronomy In the News Rusey Stuurmans Many Fertags Most NearDSuntike Stars May Form Porky Planets ASTR 1020 Stars amp Galaxies April 4 2008 Reading Chapter 22 sections 221 222 MasteringAstronomy Homework on Galaxies and Hubble s Law is due April 7 Extra credit observing at 880 amp for attending Fiske Planetarium shows Today Galaxy Evolution Last Time Galaxy Collisions Active Galaxies amp Quasars Galaxy collisions des roy i Burst of star formation uses up all the gas Le overs train wreck Ellipticals more mon in dense galaxy clusters Starburst Galaxies MilkyWayfo m 39 b r s a out 1 new star per year Starburst galaxies form 10039s of stars per year Heats dust to very hot temps glows strongly in the infrared Much evidence for giant supernovadriven Triggered by galaxy collisions Active Galactic Nuclei Active Galaxies Galaxies with strange stuff going on in their cores Bright nuclei as bright as the rest of the galaxy Quasars Quasirstellar Radiu Suuree Nuclei se brightthatthe rest ufthe galaxy is nut Easily seen 11 t discuvered as rad e suurcesr then they Were fuundtu have high redshi sl Clicker Question What is the most likely source ofthe light from bright nuclei radio visible Xrays in active galaxies a Thermal radiation from a massive star cluster Emission lines 39om hot gas 21 cm 39om hydrogen Synchrotron radiation 39om a black hole 85 D Synchrotron Only Synchrotron light is bright at both radio and Xray wavelengths 9 Active nuclei suggest a massive black hole in the center ofthe galaxy Many sh optical a emission from accretion disks Billion solar mass lack holes Galactic Jets owjets of no radio Centaurus A The Closest Active Galaxy Cygnus A Radio Jets Mme mum nhseuannns Accreticiri disk amend a massive e Disk itself may ur may nut be ubscured by dust lfbrignt VisiblE We a caii it a radlu galaxy butn a ar Artist s Conception black hcii nucleusis ricit titaqu A real example Doppler shifts from orbiting material Suggest billion solar mass black hole Another example Do ALL galaXIes have huge black holes 400 light year wide disk of material in core of an As of 2008 probably yes elliptical galaxy with radio jets Part of normal galaxy formation More quasars seen in the distant early universe than now They grow but can run out of available fuel and become relatively invisible like in the Milky Way WWWWW ResurreCted by galaxy Protogalactic Clouds collisions Many galaxies with bright nuclei show signs of being disturbed Looking for gas between the galaxies Cold invisible too Expect more such dIm even at 21cm collisions in denser early universe explain why fewer quasars today Use quasars as beacons see absorption surveys for absorption by lines from as g Intergalactic gas Hydrogen absorption at different redshifts all less than the quasar General rise in heavy elements as time goes on fountains from galaxies 7 g Keck HIRES Spectrum of Q50 14255039 mum INTENSITY g 5 E it MWHMIM no we WAVELDIGTH A ASTR 1020 Stars amp Galaxies April 14 2008 Exam 3 next class Wednesday April 16 Extra credit Fiske Planetarium shows every Thursday and SEC observing Exam 3 on April 16th Study with a buddy Chapters 193194 20 21 and 221223 Review notes on class website MasteringAstronomy assignments clicker questions key concepts Same format 20 multiple choice questions 5 truefalse and 3 shortanswer questions Review sheet on CULearn Review session during recitations 2 Be sure to bring to Exam A number 2 pencil Your CU D One page front and back of notes forthe exam A calculator Astronom Picture of the Day insz Since Yaescnve Mrmr 55 mags Lumen 2m Last Time Evidence for Dark Matter galaxies galaxy Dark mattervastly outweighs normal baryonic matter Most likely a subatomic particle wimps as yet unidenti ed Clicker Question Dark Matter is inferred to i e a We see lots of dark patches in the sky b It explains howthe expansion ofthe universe can be accelerating c We can observe its gravitational in uence on visible matter Clicker Question Dark Matteris inferred to exist because a We see lots of dark patches in the sky b It explains howthe expansion ofthe universe can be accelerating c We can observe its gravitational influence on Today Chapter 22 Section 4 Dark Matter and the fate of the Universe On Friday Dark Energy Dark Matter and the Fate of the Universe gay Expansion 4 begins with the Big Bang Several different models for Nevg dullME Wen gllnxles i v Ilmeiallltonza yul rum Important Diagram Average distanee betWeen galaxies t Expansiun faetbr t iz NOW is fixed in tirne ZZEI I Hubble nns tantNOW sets in a tne slope bftne iine new zquot WWWH wquot fast the universe is Expanding NOW me me when am Iszuo Emmy in Eutthe expansibn rate is not necessarily ebnstant fur all tirne S Lquot i Gravity Wiii SLOW i expansiun rate 9 deeeieratibn a E r g Different rnudeis fur different arnbunts bf dark ii Model Universes Recollapsing niverse Dark rnatter density eibset overnin llllnubrlwunQllniln Expansion Wiii stub in tne future Wiii nHapsE Oseiiiatiun7 Critical Universe DEHSl critical density Nu dark energy Wm expand furever but just barely awmindl lmm Mime mm n u m m mumu nl mm mm Coasting or Open Universe Has always expanded at the same rate nu deceleratan frurn gravityl Nu dark energy a density lt ermeal density Age at universe is W What is the fate of the Universe Recollapse crushing heat destruction of all matter rebirt Eternal expansion cold galaxies dimming star formation slowing everything winds up as a brown dwarf black dwarf neutron star or black hole ASTR 1020 Stars amp Galaxies March 10 2008 Reading Chapter 19 section 191192 MasteringAstronorny Homework on The Milky Way is due March 19th Wednesday oExtra credit 1 pt observing opportunities at 880 See CULearn Exam 2 on Friday covers Chapters 153 to 192 Astronomy Picture of the Day The JamesWebb Space Telescope LaunchZZEHS Mirror diameter a Semeters 21 an Last Week Star Wars Battle for Gravitational Equilibrium White dwarfs electron degeneracy pressure Neutron stars neutron degeneracy pressure Black holes gravity wins Today The Milky Way The Galactic Center Milky Way Topics Basic anatomy structure contents Looking at the Milky Way at different wavelengths Milky Way Factoids 100200 billion stars 100000 light years across Vnu are here Sun is located 28000 light years from core in the Orion Arm Milky Way Anatomy Disk includes spiral arms V granular clusters Young new star formation Bulge amp Halo older stars globular clusters splrll arms Disk is very thin Why is this an artist s conception Galaxy NGC 391quot nearly but not quite edgeon Clicker Question The ages of stars suggest that the bulge and halo of the Milky Way formed before many of the stars in the disk Which would you expect to have more heavy metals higher metallicity a Halo and bulge stars b Disk stars c No difference B Disk stars are continually forming out of gas that is more and more polluted by heavy metals The OLD globular clusters found in the halo 7 were formed a long time ago before the galaxy was so polluted they ave ve metallicities J AngloAuslrallan Observatory Contents Really Hot stuff Superbubbles amp Fountains Bubbles of hot gas blown out by supernovae T million degrees K Supernovae can burst hot gas out of the galaxy Enriches gas Mixing with rest of between galaxies galactic gas 9 enrichment with heavy elements May rain back down quot 1 V V Anists conceptionsl Fast electrons amp magnetic elds Warm stuf I 9 synchrotron Gas amp dust heated by stars emission prominent in Xray Gas emission lines from and radio hydrogen Halpha and other elements ionization Traces hot gas nebulae bubbles T10000 near hot young stars Xray image on AngloAustralian Observatory Dust Cold stuff naleAusimlL Molecular clouds Absorbs visible and UV light Dark dusty cold 1030K Transparent to longer wavelengths red IR radio Emit molecular emission lines in far Emits IR light thermal IR radio spectrum wwmnwmm Cold hydrogen Even the co dest hydrogen emth a famt rmsswon hne m the radwo Wave ength 2170mrado Change m energy eve s of nuc ear con guratwon morecmar mono Sur ngMar cycla supernovae and 5m lannauon mllzr mm a 1 323123235 The StarGas 39 quotquotquot quotquot Star Cycle ASTR 1020 Stars amp Galaxies February 22 2008 MasteringAslranamy Homework on The HR Diagram is due Feb 25 Reading Chapter 16 sections 161 63 As rr39onomy In The News SamanthaGrant Learning Assistants for Fall LAs get direct experience with teaching LAs in Astronomy can have any major LAs are paid for your teaching duties InformationRecruitment session on March 53911 from 68 pm in MCD Biology Interactive Classroom free food Today s Class The HR Diagram amp Star Clusters I Masses amp Lifetimes of 39 39 I V I 39 Stars quot I Measuring stellar ages with Star Clusters Hertzsprung Ru ssell H R diagram Stellar Properties Review Luminosity from brightness and distance 008 MSW 10 LSun 106 LSun 100 MSW Temperature from color and spectral type 008 Msm 3000 K 50000 K 100 MSW Mass from period p and average separation a of binarystar orbit 008 MSun 100 MSun MainSequence Star Summary Mam amp Lifetime Un com Mug e was a High Mass Sun 172 expectancy 1U bllllun years P ngh Lumlnoslty Lye ewecmng a 10 MM Mr shortrLlVed ar eRadlus lEI times as much fuel uses lt lEI times as fast lEI mllllun years lEI bllllun years x lEI lEI LOWMES we 2316614119 0 a1 MSW xmr Low Lummoslry n l times as mueh fuel uses it I I1 times as fast L B39L e Small Radlus lEIEI bllllun years l bllllunyears x I l I ll Red What are iants su er iants and g p g Off the Mam Sequence Whlte dwarfs Stellar pmpem39es depend on bom mass and age lhose lhat have nished fusing H to He in me cores are no longer on me main sequence All stars become larger and redder a er exhausting meal core hydrogen giants and supergiants Most stars end up small and white a er fusion has ceased white dwarfs Clicker Quesu39on Whlch ufthese What have we learned 0 What is a HertzsprungRussell diagram 7 An HR diagram plow stellar luminosity of stars Versus surface temperature or color or spectral type 0 What is the significance of the main sequence 7 Normal stars that fuse H to He in their cores fall on the main sequence ofan HR diagram 7 A star s mass determines its position along the main sequence highmass luminous and blue lowmass faint and red What have we learned 0 What are gianm supergianm and white dwarfs 7 All stars become larger and redder a er core hydrogen burning is exhausted giants and supergiants 7 Most stars end up as tiny white dwarfs a er fusion has ceased Star Clusters 0 Our goals for learning 0 What are the two types of star clusters 0 How do we measure the age of a star cluster What are the two types of star clusters Qm clustet A few thousand loosely packed stars ion or more stars In a dense ball bound together by gravity Globulzt clash Up to a mill How do we measure the age ofa star cluster What have we learned What are the two types of star clusters 7 Open clusters are loosely packed and contain up to a few Lhousan tars e Glob ar clusters are densely packed and contain hundreds ofthousands of stars How do we measure the age ofa star cluster 7 A star cluster s age roughly equals me life expectancy ofits m st massive stars sun on the man sequence mm m39 m lllulmw my mum man mu cuun llmlk39elwm tells us lts age ASTR 1020 Stars 81 Galaxies February 18 20 8 MasteringAstronomy Homework on The HR Diagram is due Feb 25 Reading Chapter15 section 152 Exam 1 February 20th h Next Class Astronomy Picture of the day Voung Sarsmthe m Uphiuch c a comm dust mm m embedded neviham 515 W 1 my WmthstamalmnvtabecalavvimtvamthEWSMce mme wulvdsunce W55 ymss Exam Study Tips Study with a friend Check PowerPoint on class website against your notes homeworks are you comfortable with the relevant concepts Do more quiz and review questions in your text and in MasteringAstronomy Check out textbook Learning Goalsquot at the beginning of each textbook Chapter and Key Concepts at end of Ch pter Review Clicker Questions Exam is closed book but you may bring one sheet of paper both sides with notes Exam 1 will cover All material discussed in class readings and tutorial up through today s class Textbook Chapters 1 Sections 1112 Chapter4 Chapter 5 Chapter 14 Chapter 15 MasteringAstronomy Homeworks on Scales ofthe Universequot Light and Spectroscopyquot The Sunquot and The Properties of Starsquot Can you use the formula Examples in class homeworks sample questions You may need to invert the equation for example solve for T using the equation wavelength 2900000 nm IT For numerical work remember units Does your answer make sense 1 nm 109 m know cm mm km The Day of the Exam Bring a 2 pencil and eraser Bring a calculator if you think you ll need one Please be prepared to get started right away at 1000 am Today s Lecture What is a HertzsprungRussell HR diagram dngum plots the luminosity and tempeutuxe of sum empeutuxe Most stars fall somewhere on the math sequence ofthe HVR diagram Clicker Question A star near the top ofthe main sequence has a luminosity about a Twice the Sun s luminosity b Five times the Sun s luminosity c 20 to 30 times the Sun s luminosity d 10000 times the Sun s luminosity Clicker QuestionA star near the top of the main sequence has a luminosity about a Twice the Sun s luminosity b Five times the Sun s luminosity c 20 to 30 times the Sun s luminosity d 10000 times the Sun s luminosity Stars With lower T and higher L than mamr sequence stars must have larger xadu giants and supelgizllts Stars wrth hrgher smaller radu White dwarfs 30mm moan 5000 mmmpmuwi n A star s full classr catton 1ncludes spectral type lrne 1dent1t1es and lum1nos1ty class lrne shapes related to the srze ofthe star I 7 supergrant V 7 main sequence Examples Sun 7 G2 V Smus 7 Al V Promma Centaurr 7 M55 V Betelgeuse 7 M2 l H7R dragrarn deprcts Temperature Color Spectral Type Lumlnosrty Radrus 4 emperature What is the significance of the main sequence Mainsequence stars are fusrng hydrogen 1nto helrum 1n the1r cores like the Sun mm mquot m Lumlnous ma1n7 Miami sequence stars are i 1quot V hot blue Less luminous ones are cooler ellow or red 1 m 7 Mass measurements of marn7sequence stars show that the hot blue stars are much more mum 7 mass1Ve than the mm cool red ones The mass ofa normal hydrogen bummg star determmes 1ts lurnmoslty and specttzl type mm 10 New A Wyn mew m wk 30000 10 Emma hemperatur lKeMm nu s can ASTR 1020 Introductory Astronomy 2 Stars amp Galaxies January 18 2008 Professor Jack Burns Newcomer All class info is at website IIII Ilsalocnl doodlll IIIIImsASIHOZOS polIndenllllnl Notes from last class are now posted on the class website 1 Astronomy Video of the Day HOV rzxsiwirw MasteringAstronomy The course ID for Astr 1020 in MasteringAstronomy is ASTR1020P08 Homework Reading Chapter 4 sections 41 44 summary of key concepts Intro to MasteringAstronomy complete by Jan 21 amp begin Scales of the Universe complete by Jan 28 Located at website httQwwwmasteringastronomyxom Register your clicker Today s Class More on Sizes and Scales and Time Reading Chapter 1 sections 11 and 12 Scales in space Looking Back in Time Scales in Time History ofthe Universe Powers of 10 26 powers of10102E Measuring distances with light Measuring cosmic distances EarthMoon 15 lightseconds Most use Jl measure is based on the Speed Of light 3011000 kmSec EarthSun aka astronomical unit or AU a light minutes Like saying I live 30 min from Boulderquot Solar system light hours Constant speed forlight traveling in space Nothing travels faster through space Nearest stars uver4 llghtryears Over astronomical distances even light takes a lot oftime from a human s Mlle Way manna llghtyears lEI5 ly perspective to travel between the stars Lucal gruup several mllllurl llghtyears l DE ly This means that what we SEE in the distant observable unlverse l4 bllllurl ly l4 gtlt lEIl ly lin39verse 395 quot9 that has traveled a I quot9 Our image ofthe universe is a delayed image In looking out into space we are also looking back in time What we SEE is away5 deayed by the Clicker Question The image of the Sun is speed of light In the c assroom ourview old ofeach other is only about 10395 seconds 000001 sec old so we barely notice a 1 second b 1 39 t Satellite communications noticeable delays mfnu e c 8 minutes Delay in Communications between Mars d 1 m th39 and Earth39 t 2 x Dc 507 sec 84 e 1 year minutes D MarsEarth distance 76107 km c speed oflight 3x105 kmsec Clicker Question The image of the Sun is old a 1 second b 1 minute c 8 minutes d 1 month e 1 year The image of a galaxy spreads across 100000 years of time Try to think of what we SEE NOW as different from what may EXIST now A Brief History of the Universe About 14 billion years ago everything was unbelievably hot and dense Conditions were too extreme for normal matter to exist Then space started to expand This beginning is called the Big Bang After the universe cooled hydrogen gas and other norm al matter form ed Gravity began to pull this gas into balls that became stars Gravity pulled the stars into larger structures called galaxies Gravity keeps galaxies and tars about the sam ize but the universe is s s farther away from each other The stars process hydrogen into other elements via nuclear fusion Supernovae explosions disperse these other elem ents throughout the universe This is the origin ofnearly all elements including all of the carbon oxygen etc in your body Starsfurm burn hydrugen mm Either elements and explude m disperse the Material El make NEW stars 1 Inside galaxies planetary systems generations of stars History of the Universe how long did this all take Use a 12 month calendar as a model for the 14 billion year history since the Big Bang 1 Jan Big Bang Late on Jan 15 hydrogen forms MidFeb Milky Way galaxy forms FebAugust stars are born and dIe in the the galaxy Sept 3rd Sun and solar system form Late Sept life begins Dec 26 Dec 30 dinosaurs Dec 315 9pm human ancestors walked upright 11 sec a 0 Egyptian Pyramids 005 sec ago you were born The Big Bang was about 14 billion years ago 9There is a limit to how far out we can SEE equal to about 14 billion light years 9The 14 billion light years in all directions is the observable universequot 9The actual universe may actually be Igger or in nite We simply run out oftime to see it