ASTR 1120ASTR 1120General Astronomy:General Astronomy:Stars & GalaxiesStars & Galaxies•• FINAL:FINAL: Saturday, Saturday, Dec 12th, 7:30pm, HEREDec 12th, 7:30pm, HERE••ALTERNATE FINALALTERNATE FINAL: Monday,: Monday, Dec 7th, 5:30pmDec 7th, 5:30pminin Muenzinger Muenzinger E131E131•• Last OBSERVING session, Tue, Dec.8th, 7pmLast OBSERVING session, Tue, Dec.8th, 7pm•• Please check your grade on clickers, midterms, Please check your grade on clickers, midterms,HWs HWs on CU learn - e-mail Thomas if you seeon CU learn - e-mail Thomas if you seediscrepancies/missing gradediscrepancies/missing grade..Review of the CourseReview of the CourseFour general topics:Four general topics:1. Intro: Scales, matter, light, telescopes1. Intro: Scales, matter, light, telescopes2. Stars2. Stars3. Galaxies3. Galaxies4. Cosmology/Dark Matter/Universe4. Cosmology/Dark Matter/UniverseTo develop a To develop a broad viewbroad view of ofwhat we know about thewhat we know about theUniverseUniverseTo understand To understand the forcesthe forcesthat shape the Universethat shape the Universeand its historyand its historyTo help you understandTo help you understandhow we figured all thishow we figured all this outoutToTo learn how learn how sciencescience works worksCourse GoalsCourse Goals1. The Scale of the Universe1. The Scale of the UniverseMatter: AtomMatter: Atomnucleusnucleuselectronelectronee--protonsprotonsneutronsneutronspp++nnLight:Light: our main source of our main source ofastronomical knowledgeastronomical knowledgeThe Electromagnetic spectrumThe Electromagnetic spectrumThermal Thermal (black body)(black body) Spectra Spectra••Emitted by allEmitted by allsolid/opaquesolid/opaque objects, objects,including stars,including stars,planets, humansplanets, humans••Smooth, broadSmooth, broadspectrum rising to aspectrum rising to apeak at somepeak at somewavelengthwavelength, where, wheremost of the radiation ismost of the radiation isemittedemitted––WienWien’’s s LawLaw––Stefan-Boltzmann Stefan-Boltzmann LawLawSpectral lines:Spectral lines: By atoms emitting By atoms emittingor absorbing PHOTONS = lightor absorbing PHOTONS = light••The energyThe energychange betweenchange betweenlevelslevels is equal to is equal tothe energy of thethe energy of thephoton.photon.••Remember-Remember-larger energylarger energyjumps will bejumps will beSHORTERSHORTERwavelengthwavelengthphotons!photons!TelescopesTelescopes••Refracting Refracting vs vs ReflectingReflecting••Size matters:Size matters:––Light gathering powerLight gathering power––Angular resolution (diffraction limit)Angular resolution (diffraction limit)••Telescopes are built differently for differentTelescopes are built differently for differentwavelengths: ground-based, airborne and spacewavelengths: ground-based, airborne and space1.1.What is the Sun made of?What is the Sun made of?2.2.How does the Sun produce its energy?How does the Sun produce its energy?3.3.Which forces keep the Sun inWhich forces keep the Sun inequilibrium?equilibrium?4.4.WhatWhat’’s inside the Sun?s inside the Sun?5.5.What will be the end of the Sun?What will be the end of the Sun?6.6.How massive is the Sun?How massive is the Sun?Stars: Starting with our SunStars: Starting with our SunStarsStars••Shine with energyShine with energyreleasedreleased from from fusionfusion––hydrogen fusing intohydrogen fusing intoheliumhelium••Overall fusion rate veryOverall fusion rate verystablestable––gravitational equilibriumgravitational equilibrium••Violent activity on theViolent activity on thesurfacesurfaceMeasuring the StarsMeasuring the Stars••Estimating distances viaEstimating distances viaparallaxparallax••Inverse square law forInverse square law forbrightnessbrightness––Apparent brightness andApparent brightness anddistance distance !! luminosity luminosity••Measuring temperaturesMeasuring temperaturesvia color, spectral typevia color, spectral type––OBAFGKMOBAFGKM••Measuring masses viaMeasuring masses viabinary starsbinary starsThe Hertzsprung-Russell DiagramThe Main SequenceThe Main Sequence••StarsStars spendspend most ofmost oftheir lives heretheir lives here••More massive stars areMore massive stars are––RarerRarer––Hotter/BluerHotter/Bluer––BrighterBrighter––Shorter livedShorter lived••Can estimate ages ofCan estimate ages ofstar systems fromstar systems from““main sequencemain sequenceturnoffturnoff””Stellar EvolutionStellar Evolution1.1.Star BirthStar Birth2.2.Main SequenceMain Sequence3.3.Series of expansionsSeries of expansionsand deflations inand deflations inresponse to coreresponse to corenuclear burningnuclear burning••Low mass stars:Low mass stars:––Red giantRed giant––Horizontal branch starHorizontal branch star––Planetary nebulaPlanetary nebula––White dwarfWhite dwarfStellar EvolutionStellar Evolution1.1.Star BirthStar Birth2.2.Main SequenceMain Sequence3.3.Series of expansionsSeries of expansionsand deflations inand deflations inresponse to coreresponse to corenuclear burningnuclear burning••Low mass stars:Low mass stars:––Red giantRed giant––Horizontal branch starHorizontal branch star––Planetary nebulaPlanetary nebula––White dwarfWhite dwarfHigh Mass StarsHigh Mass Stars••Very rapid sequenceVery rapid sequencefusing heavier elementsfusing heavier elementsup to up to ironiron––Core unsupported =Core unsupported =collapsecollapse••Supernova explosionSupernova explosion––Blasts heavy elementsBlasts heavy elementsback into spaceback into space••Neutron starNeutron star or or blackblackholehole remains remainsStellarStellarGraveyardGraveyard••White dwarfsWhite dwarfs––and the possibility ofand the possibility ofwhite dwarf supernovaewhite dwarf supernovae••Neutron starsNeutron stars––possible pulsarspossible pulsars••Black HolesBlack Holes––Detected only by theirDetected only by theirinteractionsinteractionsStellarStellarGraveyardGraveyard••White dwarfsWhite dwarfs––and the possibility ofand the possibility ofwhite dwarf supernovaewhite dwarf supernovae••Neutron starsNeutron stars––possible pulsarspossible pulsars••Black HolesBlack Holes––Detected only by theirDetected only by theirinteractionsinteractionsStellarStellarGraveyardGraveyard••White dwarfsWhite dwarfs––and the possibility ofand the