STARS,GALAXIES&COSM ASTRO 150
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Astro 150 Astronomy Picture ofthe Day ma Reading Chapter is amp Chapter 6 6 5 Review of last time Stellar Classification quot simplv more distant versions of our Sun They can be more or less m i They can be at different stages oftheir life Stellar Classi cation ased upon surface temperature and luminosity hluer H leader hnller cnnler ezrly lypeslzls lzlequotlypeslzls E g e a E Wavelslwln 1A 1 A in rim Spectral Sequence is a Temperature Sequence m m m Almusnhm ol Eelelgeuse x m4 myquot m sxwom m m ms Q HST can take pictures in the ultraviolet optical and infrared so why was this picture taken in ultraviolet light Luminosity total energy outputtime ergsls Watts Apparent brightness what we can actually observe depends on luminosity and distance 1 Observe brightness 2 Determine distance Luminosity 41 Distance2 x Brightness a small detail We ll talk about on Thursday Am isn Svnnv Inns cm H Dive 5 Finding the Distance to Nearby Stars Parallax distant slab d 1p d parsecs p arcseconds 1 pc 326 ly July A Limited by ability to measure small angles Ground Based to 100 pc 001 arcsec error 1 Cygni a ax first measured parallax 1838 0314quot 0292quot 104 Iy 112 ly 61 Cygni 0292quot 112 ly 0c Centauri 075quot 43 ly Vega 0123quot 26 ly Bessel 1784 1846 Barely visible to the naked eye Why did Bessel pick this star The Flying Starquot 52quotyear Am isn Svnnv Inns cm H Dive x Motion of Stars in Space and in the Sky Stars are really moving typically at 10 s of kms eg Sun moves at 20 kms relative to nearby stars But because of their distance they appear not to move Radial Velocity Tangential Velocity Proper Motion Proper Motion angular shift in stars s postion Due to its motion in space typical 01 arcsecyr Pr three bright stars Sirius Aldebaran and Arc The Big Dipper Given enough time even small proper motions become visible oper motions were rst noted by Edmund Halley in 1718 for turus Motion of Stars in Space and in the Sky Proper motion depends on star s tangential velocity and distance 84 On average close stars will have higher proper motions Good wayto identify stars that can be observed with parallax eg arnard39s star 1025 arcsecye r 6 ly 61 Cygni a 52 arcsecyear 10 ly Radial Velocity and the Doppler Shift Radial Velocity and the Doppler Shift so Stul39i 3 Brown M Shift is independent of distance Depends only on velocity of object Am lsn Svnnv Inns lawn u Dive 3 Am lsn Svnnvz s lemme u met Using parallax and spectroscopy we can determine luminosity and surface temperature for nearby stars Stellar Rotation and the Doppler Shift ll Llle t aal39 Narrow spectral lines tndtcate that star A rotates slowly lnlenslly wavelengln wavelength lms light IS slightly redshllted to Earth last mlaa39on gt Ims light ts greatly blueshllted intensity m p w e V A v intensity V l s s at indioah lha MB A rotates rapidly wavelengm wavelength lhis ltgm is greatly led 1 leading a Emu Slds Same idea used in measuring rotational period of a planet Stars within 125 ly of the Sun Am lsn Svnnv Inns lawn u Dive 5 Am lsn Svnnvz s lemme u vive la Parallax measurements from space allow us to measure the luminosity What is thiS ttHertzsprungRusseiiu Diagram of much more distant stars Hurlnltrltl Rumll m Stars out to Plot of luminosity vs surface temperature for stars 500 pc 1630 ly 0 a a Race Cars Hipparcos satellite 0 o e 39 e 39E 39 o 00 Sports Cars E E 8 3 g 3 g 8 000 Q o a g 39 2 a Normal Cars 3 39 39 Temperature SpT Economy Cars v Weight Using the HR Diagram to Obtain Distances Stars move around on the HR diagram as they evolve and change their luminosity and surface temperature 039 39 39 HR Diagram quot6 For People a E quot53 g l eg A0 v width of lines related to luminosity 7 Weight 1 Observe spectrum 2 Classify star 3 Determine Luminosity from HR Diagram Luminosity 47 Distance2 x Brightness This technique is called spectroscopic parallax You observe this computer model of the rst few moments of a Supernova iron core rebound expanding shockwave TFm Crab Nebula 39 opticakFitk Neutron Stars 0 M gt L4 Msun collapse pastWD core 0 nuclei packed tightly together 0 protons absorb electrons only neutrons left 0 collapse halted by neutron degeneracy pressure 10 6 4 X 1m 5 M 1 4 Msun R 1020 km density 1014 gramscc Donslu gmmli Radius km 1 teaspoon of neutron star 4X mu I all the people in China walk L 0 How do you find something so small Neutron Stars Mass 20 M sun Radius 000002 R sun Temperature 5x05 K L R 2 T 4 LSUI39I RSUI39I TSUI39I so LLsun 000I nearly all in Xray SMALL DIM and RARE end product of O B star evolution means 0 closest is still pretty far away 0 very unlikely to see in optical or even Xray 0 concentrated and extreme stars isolated neutron stars rst seen only recently I 997 Isolated Neutron Star RX J1 856353 r A 39 V l A o 1 l 391 Neutron Star RX J1856353754 H T I WFPCZ PR097 32 ST Scl OPO September 25 1997 F Walter Stale University of New York at Stony Brook and NASA wh does the Crab Nebula shine 39 The Crab Nebula optical Fick 39 remnant of SN in 054AD Discovery of Neutron Stars Pulsars I967 O l9 7z Tommy Gold and Franco Pacini 0 why does the Crab nebula shine supernova leaves a rapidly rotating neutron star neutron star has an intense magnetic light produced by motion of e39 in magnetic eld energy for light derived from NS rotation spin rate should decrease with time 4 diation Jng ra field a k ed 9 The GoldPacini model 0 Concentrated ROTATION 0 Radius shrinks from Rsun to lO395 Rsun 0 Spin rate increases as lRZ or by a factor of IOIO 0 scaling from the Sun s rotation I month 3xlO6 sec gives a rotation rate for a neutron star of 03 milliseconds 0 lots of energy available from neutron star rotation O Concentrated MAGNETISM 0 Magnetic eld of Sun IO Gauss Field strength increases as lRZ or by a factor of IOIO scaling from the Sun s magnetic eld gives a eld strength for a neutron star of IOquot Gauss for comparison 0 Earth magnetic field l2 Gauss compass needle I Strongest permanent magnet l4000 Gauss O Strongest magnetic field produced 4xl05 Gauss The GoldPacini model 0 Rapid Rotation Strong magnetic field COSMIC GENERATOR ACCELERATOR 0 central engine surrounded by ionized particles electrons protons ions 0 particles constrained to move along magnetic field lines 0 crash down onto NS poles heating up the material 0 additional radiation via synchrotron radiation rotation age The GoldPacini model 0 New Neutron Stars MUST rotation Eng rotate rapidly have strong magnetic fields pump out energy via synchrotron radiaton energy lost must come at expense of rotation so rotation must slow down with time o Rotating neutron stars could must be the energy source for glowing supernova remnants 13 Discovery of Neutron Stars Pulsars I967 0 I967 S jocelyn Bell discovers a radio signal regularly pulsing 6 A 1 TM rapid gnu CPU 339 I once every 33 seconds PSR 0329 We a quotf O extraterrestrial 072 s 7 s aliens LGMI LGMZ l atgminmhwwiiwm J 0 nowhynot 2 39 539 l 2 l 39 39 t I Vela quotr 39 11 o I NGUtI OII stars 0089s I974 Nobel Prize to Tony Hewish Bell s advisor 2 Neutron Star spindown O Rotational Energy E o E02 R2 o olt2Q R2 LOCBQ lose energy lt 0 spin down lt 0 0 energy loss rate from nebular and pulsar emission allows an estimate of the spindown rate expected for pulsars 0 Over time spin rate drops so energy available drops 0 Pulsars should SLOW DOWN and FADE with time 0 Magnetic eld drops also leaks out Pulsar Evolution 0 magnetic eld decay spin down dropping luminosity 0 young pulsars are 0 fast 0 bright 0 fast spindown rate 0 strong magnetic eld 0 old pulsars are 0 slow 0 dim 0 slow spindown 0 weaker magnetic eld 0 the pulsar death line 0 no more ee production spin down rate APAt sen A s 5 a 7315 416 4M 412 418 l l 001 Measuring SpinDown O m is the thing that we can measure most accurately 0 measuring period change directly is very dif cult 0 but period change ltgt accumulating delay in pulse arrival time 0 ie slow clock by ll0000 0 beatbybeat is the same to O millisecond BUT O in day clock is 86 seconds slow 0 in week clock is l minute slow 0 growing effect when compared to reference signal 0 ticks lengthen will get out of sync with lousy clocks eventually 0 reference clock needed pulsar is its own reference 0 Pulsars are the BEST CLOCKS in the UNIVERSE 17 Pulsars a new tool for astronomy and physics Crab Pulsar 0033 s 0 Binary Pulsars precise tests of general relativity I993 Nobel Hulse ampTaylor 0 Pulsars with Planets timing jitter gt planetsized companions AlexWolsczan 0 Millisecond Pulsars 0 fast pulsar small dPdt PSR I937 00067s 0 recycled pulsars spunup by companion Don Backer 0 should have companion most do many do not 0 Black Widow Pulsars pulsar blasts away its companion Dan Stinebring Gamma Ray Bursts O shortduration high energy flashes 0 O to ICC seconds lillllllllllll I 3 U U I I EU 7 39 Lquot V o 4 ti 2 200100 0 m 4 LJ w fr V E l g 5 Ed m w 100 I I E J I 4U E V 7 I 0 r 1 il llJiL f rjrlldlll i liii 1 1 l 11j l lJHi ll l CI 07 3 Mil OIJCL 30 1239 PSI 53 rmr vrm mwm nm 1 1 l 1 I 1 1 l A 1 x 1 l 1 Gamma Ray Bursts O shortduration high energy flashes O evenly distributed across the entire sky 0 cosmological distances intensely bright supernovae 2704 BATSE bursts 10 7 10 6 10 5 10 4 Fluence 50300 keV ergs cm39z Gamma Ray Bursts O shortduration high energy flashes O evenly distributed across the entire sky 0 cosmological distances hypernovae 0 rapid rotation gt accretion disk 0 relativistic jet collimated by accretion disk 0 beam points towards uswe see gamma ray burst 20 Astro 150 Astronomy Picture of the Day Saturn s moon Titan from 8km altitude CassiniHuygens Mission Reading chapter is Sectan is 2 uptu dlstarie 3 chapters Sectluns 6176 4 Exam i THHNHZ Fthan in Brief review of last time Newton Forces and Light Newton s Laws physical laws ofmotlori law of universal gravitation and Kepler s laws explained Cosmic Forces Light Eieotrorn agnetio Radiation the only way to learn about the stars and beyond wavelength frequency and speed speed or light 30000 llt is differentwayelerigth dirrerentcoior The Electromagnetic spec rum visiblellght 400 nrnto 700 nrn usable light 000i nrnto i0 km WARNING This room is currently awash in Electromagnetic Radiation Radiation energy being carried through space If the energy is being carried by light we call the radiation electromagnetic radiation Note Some high energy forms of light are dangerous eg gamma rays Xrays ultraviolet easurinq Liqht Luminosity total rate of energy emission intrinsic to the object eg star light bulb 7 DUNKquot ergs per second 39 time joules per second watt Brightness rate of energy passage through a xed area 7 l umimiadr K 7 illsxam m depends upon distance INVERSE SQUARE LAW OF LIGHT Particlelike Progerties of Light 18901905 early quantum mechanics Radiation from solids Planck Interaction oflight with solids Einstein Light propagates as if it were a wave but in eract with matter in some ways as if it were a stream of particles WAVEPARTICLE DUALITY OF LIGHT light is made ofparticles called photons energy ofphoton is proportional to frequency pnmun High Frequency short wavelength high energy photon m Low frequency long wavelength low energy photon Bright light log of photons ut after all there is really 39 bout es so that ifthe rabbit were only cat we would understand its behavior perfectlyquot cllnlanl Davlsson eNobel pllze Wlnnel my Physics 1937 Photons Particles InterferenceDiffraction Waves Continuous S ectrum emitted by hot opaque objects aka thermal radiation or blackbody radiation a Ihnghmessl hlue um Ed 1 lwmelenwlhl emits a continuous spectrum spectrum shape determined by temperature only particles move faster interact at higher energies 23 x 10 i produce higherenergy photons Properties of Thermal Radiation Wien s Law increase Temperature and Rule 2 in textbook Object Temperature wavelength of max Band Sun 5780 K 500 nm visible you 310 K 9400 nm infrared neutron star 10000000 K 03 nm X ray Which object has the highest T Which object is brightest in the ultraviolet lt 400 rim the visible 400900 rim the in 39ared gt 900 rim Mam brightness o o much energy per unit area Temperature and surface area Properties of Thermal Radiation StefanBoltzmann Law Hotter objects are brighter at all wavelengths I Energy emitted per unit area T Luminosity of an object depends on uminosity R2 T4 Rule 1 in textbook Double an object s temperature and it emits 16 24 times as Stars are close approximations to black bodies Wien s law Amax 1IT says a star s color tells you its temperature red stars are cool T lt 5000K blue stars are hot T gt 10000K StefanBoltzman Law L R2 T4 says two stars with same radius blue star more luminous than red star These two stars are at the same distance from us How can they be the same brightness 2 2 2 A more realistic stellar spectrum Stellar Spectra show a continuous spectrum continuum DARK LINES Gustav Kirchoff s Laws 185051 1 Continuous spectrum solids liquids and hot gasses at high pressures 2 Emission Bright Line Spectrum hot gas at low pressure 3 Absorption Dark Line Spectrum transparent gas in front of continuum source A single element makes emission and absorption lines h at the same wavelengt s continuous B emission line A 4 absorption What causes spectral lines WITHIN atoms electrons are confined to a fixed set of energy levels One way electrons can change energy levels by emitting or absorbing energy in the form of photons Photons involved must have energy that is precisely equal to difference between two atomic energy levels small energy difference low energy photon large energy difference high energy photon Atoms produce and absorb photons at specific energies i E3 0 e ission 71 E1 absorpti n EziEl E1 ym ll Ionization high energy photon strips electron from atom Recombination atom recaptures electron photon emitted absorpti n Hydrogen atom energy levels ionization E 3935 eve 5 1 leveIA v V 130 eve3 I I I 6 Q 27 l l l l levelz N N K 5qu 102 ro n 6 N Energyievi P v la d 616 50 9 s m r re vinhlw levelt on A 7 0 ultraviolet Reading Chapter 6 section 65 m a ter l6sections l6l l65 p OBAFGKM Contest a better mnemonic for OBAFGKM I written or email entries due thisThursday October 7 I judging by an independent panel I prizes 15D FeliZEEIA L mi Brief review of last time Distances II the HR Diagram Statistical Parallax motion of the sun for a bigger baseline Stellar Motions 0 Proper motion and tangential velocity 0 RadialVelocity via the Doppler Effect 0 space velocity Distance via space velocity tangential velocity gt distance Ranges of stellar mperties The HertzsprungRussell HR Diagram 0 classi cation tool luminosity plotted vs temperature 0 radius on the HR diagram 0 biggest stars in upper right corner izpag l 0 The Main Sequence 0 diagonal band 0 90 of all stars are Main Sequence stars 0 The Giants 0 upper right 0 high L lowT gt huge size 00 Rsun and more 0 White Dwarfs 0 lower left 0 low L high T gt tiny size 00l Rsun and m lSDRAHZEEIAL mi izpag 2 Features on the HR Diagm less m l EIFaiiZEEIA L mi Features on the HR Diagm spectral type A F 20000 10000 5000 lt TemperatureK O B G K M 106 v R dG39 re Iants 104 0 102 0 s TheMai a 1 Sequence O 3 10392 10quot 10396 izpag a An HR diagram for all stars with Hipparcos parallaxes distance limited m l EIRAHZEEIAL mi izpag A An HR diagram for the mghtest stars in the sky brightness limited on iquot It lt L I Hi ll TDDOD in IE 5 HE H Surface temperature M D GIANT E E 3 g 10 1 x Caniauri r2 7 Sunquot r mum a f r 55quch 1 R32 1 001 V 39 01 0001 i g l l i 30000 10000 6000 3000 m i EIFaiiZEEIAL mi 12mg 5 Main Sequence stars are the most numerous BUT The most prominent stars in our sky are the rare but luminous blue main sequence giants and supergiants 0 Why such variety 0 What makes stars so different from one another 0 What are we missing MASS m i EIRAHZEEIAL mi 12mg 6 Measuring Stellar Masses Binary Stars 0 Epler s Third Law for binary stars 3 M1M2 orbital period yrs 0 The See Saw Law centerofmass amp a 0 M02 M2 d1 d1 d2 0 sum and ratio of masses allows determination of the individual masses of each star Iypes of binary stars W 0 Visual 0 widely separated l0l00 auand more 0 knowdd2 dZdl P sometimes 0 39 0 Spectroscopic 0 spectral lines show periodic Doppler shifts 0 too close to see individual stars 0 know dZdl from velocities P 0 Eclipsing 0 brightness variations as stars eclipse one another 0 know P shapes of stars light distribution 0 Eclipsing spectroscopic rare 0 provide dd2 dZdl P and so masses 0 radii from eclipses and orbital velocities 0 Astrometric 0 stars that wiggle 0 bright star orbiting an unseen companion Provides d2 p aciualmoilon mean run m i EIRAHZEEIAL mi 12mg Castor a visual binary m i FsliQEIm L w IQDsa 9 0 Double line spectroscopic binary A doublelined Spectroscopic Binary star 0 Eclipsing binary W 500 mm W 50 IIqu WI see mm We 59 mm Hum mm Imm All ml E Imm lmili me lmm A A and B mm m A A and a appamu Uiigllli39ess m i FsliQEIm L w IQDsa in 0 more than 50 of stars are in binary or multiple systems 0 BUT only a few dozen can be used to measure accurate stellar masses 0 Q1 Obsewation Stars with the same mass have the same spectral type on the Main Sequence m iiiFsliQElm L w IQDsa ii Q1 Observation Stars with the same mass have the same spectral type on the Main Sequence spectral type 6 O B A F G K M 1 quot20 Msun to gt 104 31 H r I 102 i 2quot 395 g 1 7 5M5quot1 II 3 102 104 1o 6 I I I 20000 10000 5000 lt Temperature Kl Properties of Main Sequence Starsm w juagga Lll39sun MMsun RRsun Example I 260000 20 I 0 Rigel I 00000 60 3 25 Vega I 000000 I I I Sun Capella 5000000 006 04 06 3322quot 0 Lower mass limit of Main Sequence 008 Msun 0 stars less massive don t get hot enough to burn hydrogen 0 Upper mass limit 200 Msun o if M gt IOO M violently unstable sun m i EIRAllZEEIAL ml izpag 14 Main sequence Extremes The MassLuminosity Relation ronger l er ressure neidedllo maintainHSE 0 arm erlor orerapl energy HIgherLumInosny Eddingt I 926 4 L 0 M for main sequence stars VumALu n An mu 0 Main sequence is a sequence in MASS blue stars are more massive than red stars The Sun is a MS star I I Zim 39s39mgfgzggigzgm 0 The Sun burns hydrogen in its core Pistol glapui and Masslvo Star HST NlCMOS my mama 5am mm 0 all MS stars burn hydrogen in their cores The MassLumInOSIty Relation TheVogt RussellTheorem I926 Properties of ordinary stars are 10 Brighwgkmsm determined uniquely by mass and 7 39 composition 1047 LM4 quot 7 it quot MassComposition gt position in HR diagram on MS star burning hydrogen BUT star is voluntarily changing its composition Sun mass 1 Me I luminosity i 3 0 star must leave MSwhen hydrogen is exhausted Dim lowrmasssiars y i 0 so stars must move in the HR diagram as they age ll VR theorem demands luminosiiy in solar luminosllles 9 l0 Mass in solar masses MQl I 0 Stellar Evolution Reading Bennett SKIM Chapter 2 Section 26 Chapter 3 Sections 3335 3 Chapter 5 Sections 5 5 Chapter 6 Sections 6 64 Exarn Thursday February IO Ash 15D SpingZDE L m 2mg 1 Brief review of last time Scales of the Universe Nearest starzAlpha Cen d4x03km 40 trillion km The LightYear Io393km Milky way dimensions 00000 Iy IO Stars in galaxy o I IO I Galaxies in the Universe 0 Composition 80 hydrogen 20 helium Universe is mostly empty space density IO across IOOO Iy thick Nearest Spiral Galaxy M3 in Andromeda d2 million Iy 23 glcm3 lt impurities Time scales of the Universe age 36 billion years m l SpingZE L m 2mg 2 Occam s Razor Willamfoccmmoa We take as Truth the simplest explanation that fits all of the data This is the fundamental principle of all modern science Today The Discovery of Gravity prehistorybGreeksgtCopernicus gtTychogtKepler a GalileopNewton Looping Planets Movlh Easi Dun norm mailers Bauman mm a lmm mm mm ml to m m l SpingZE L m 2mg 4 The Early Days 0 Prehistoric Discoveries 0 Motivation Calendar survival Cosmology order higher being 0 Ecliptic Zodiac paths of planets and Sun 0 Solstice seasons 0 Saros cycle eclipses 0 Early SciencezThe 500 BCE I50 CE 0 spherical Earth Pythagoras 0 model of celestial motion Aristotle 0 relative dimensions of Sun Moon Earth Aristarchus Aslr 1503pnng 005 L lur 2pag 5 Philosophy m observation culminated in 0 Ptolomy s computational scheme for celestial motion 0 Earth centered 0 Uniform circular Motion 0 Epicycles Aslr 150 Sprin 2005 L lur 2pag e 0 IZOOs Ptolemy s method off by several degrees 0 response add more epicycles 0 l543 Copernicus 0 moved sun to center gt Revolutionary 5801Tycho Brahe 0 precise positions of planets 0 stars are xed therefore very distant 0 sky is not immutable 0 I609 Galileo 0 astronomer telescopic studies show Copernicus was right 0 physicist experiments with Gravity Aslr 1503pnng 005 L lur 2pag 7 l6l0 johannes Kepler mathematician and klutz used Tycho s data on the motion of Mars with no circular motion bias to discover Epler s Laws of Planetarv Motion These are simpe empirical laws explaining planetary motion derived from data only with Q preconceptions Aslr 150 SpringQOOS L lur 2pag Kepler s Law I SUN ma 0 Planets orbit the sun in ELLIPTICAL orbits around the sunwith the sun quot quot iquot939iquot quot quot s at one focus of the ellipse 0 noncircular motion Kepler s Law 2 0 A line joining the planet to the Sun sweeps out Eual areas in equal times so planet moves faster when closer to the Sun 0 nonuniform motion Aslv lanSpngDD L nu 2mg 9 Kepler s Law 3 0 The Law of Periods Period2 semimajor axis3 P2 3 a P in years a in AU Bigger orbit larger a gt longer Period m ran SpngDD L m Zpag m Kepler s 3rd Law Planet Py aau p2 a3 Mercury 024 039 0058 0059 Venus 062 072 038 037 Earth I 00 I 00 I 00 I 00 Mars I 88 I 53 353 358 Jupiter I 90 53I I42 4 Saturn 2930 955 870 87 I Uranus 84 I9 I 9 7056 7067 Neptune I 648 30 27 I 50 27000 Aslv lanSpngDD L nu 2pa3 II I 666 Isaac Newton mathematician Invented calculus as a youth SYNTHESIZED Galileo s Experiments Kepler s Laws Calculus into Physical Laws the basis of Modern Science Apple falls gt Earth and apple attract each other Moon and Earth attract each other too m 15D SpinyZDD L m 2mg 12 escape velocity orbital velocity cnpvaoznm a a aaaaaaaa mum If moon moves sideways as it falls it could forever circle the Earth Reading Chapter I8 Sect I883 m i usmngauu L luv i7psg i m i usmngauu L luv i7psg 2 OBAFGKMWinners N Exam 2 Thursday after break March 24 essay next Tuesday Mass 20 Msun Brief review of last time Stellar Evolution II 39 White Dwarf Stars Radius 000002 R 0 hot but faint gt very small Sirius B 5 n 0 supported by electron degeneracy pressure N 5 0 evolution through cooling Temperature SXI 0 K 0 Final evolution 8Msun lt M lt 25Msun L R 2 T 4 0 burns C etc but with diminising ef ciency LsunRsun Tsun 0 onionskin structure 0 iron burning eats energy 0 Supernova 0 iron core collapse rebound in seconds so LLsun 000I nearly all in Xray 0 synthesis of all heavy elements rarity of neutron stars end product of O B star 0 expanding supernova remnant evolution means 0 Neutron Stars closest is still pretty far away 0 supported by neutron degeneracy o M 2M R 20 km density IoI4 gcc sun 0 small and very faint very unlikely to see in optical or even Xray Discover of Neutron Stars Pulsars 1296 3 0 I967 S locelvn Bell discovers a radio signal I V 39 0 regularly pulsing 39 39 P quot 7 CT 0 rapid 39 39 once every L33 seconds PSR 0329 0 extraterrestrial 0725 0 aliens LGMI LGMZ Neutron stars I968 Tommy Gold and Franco Pacini 0 pulsars are rapidly rotating neutron stars 0 beaming by e39 in magnetic eld 0 NS rotation sweeps beams 0 con rmed by measures change in spin rate I974 Nobel Prize to Tony Hewish Bell s advisor 2 rotalion axis M gt 25 M sun 39 imn om gt 5 MWquot even neutron degenemcy zn39t stop collapse Binary Pulsars recise tests of geneml relativity has Nobel Mammy 0 complete gravitational collapse to BLACK 0 Why black HOLE P3Rl937 o Mllllsecond Pulsars Bums Esffpe vjli quot m h recycled pulsars spunup by companion palatal 533 m m in 15 lavs i mum mph urns anew 0 Black Widow Pulsa 39 M an on an no mass m quotmm pulsar blast away its companion on sunning 0 I783 o Mitchell Pulsars Wm Planets escape velocity gt speed of light when timinz iitterquot gt planetsizedcomnanions wanna R lt R sun m The Black Hole Environment 0 NOTHING can travel faster than light o the ultimate speed limit is 300000 kms o Dangerous tidal forces are enormous o near Black Holes light cannot escape o no light no information EVENT HORIZON point of no Ntum t n a Anythingtlatenterst e Event Horizon loses contact with the rest olthe Universe lorever o Life near a Black Hole lar outside d gtgt Rx leel gravity as elsewhere just outsidestidallorces inside d lt RR cut offfmm Universe m iEDSVVEQEID L w Mag 9 The Black Hole Environment 0 Dangerous tidal forces are enormous Black holes and time machines Monster Black Holes in Gala Cores The Black Hole Environment 0 Dangerous tidal forces are enormous 0 strange Views gravitational bending of light 0 warped time gravity near a black hole slows down time with respect to outside observers How can we nd a black holequotW 0 They exert a gravitational force nd a binary star with an unseen companion M gt 5 Msun 0 They suck sortof 0 surrounding matter may fall into the black hole 39 quots 0 gas falling in gets squeezed 0 heats up 0 glows as X Rays 0 Best candidate Cygnus Xl o visible star 09 20 M sun spectroscopic binary companion 0 Msu n 0 copious Xray emission Spectrum of Gas Disk in Active Galaxy M87 Approachlng Receding Hubble Space Telescope FalntOblact Spectrograph Ashalf SpingZDE Lechuel pagel Reading Chapter l6 section l66 hapter l7 Sections I7 I l 73 OBAFGKM Contest a better mnemonic for OBAFGKM I written or email entries dueTODAY I judging by an independent panel I prizes Brief review of last time HR Diagram Groups Stellar Mass 0 Radii on the HR Diagram 0 HR Diagram FeatureszThe Main Sequence Red Giants and White dwarfs I 90 of stars are on the Main Sequence I most prominent stars are very rare but very luminous 0 Determining stellar masses Binary stars I Kepler39s 3rd law combined with seesaw law I types of binary stars eclipsing spectroscopic binaries are the best 0 Main Sequence a sequence of mass 0 high mass stars are OB lowest mass are KM 0 Limits of the Main Sequence 0 The MassLuminosity relation Ashu LED Sping 2mm Lame is page 2 The MassLuminosity Relation tronger l er ressure N neidedllo maintainHSE o erin erior orerapi energy Higher Luminosny 0 Eddington I926 L 0 M4 for main sequence stars 0 Main sequence is a sequence in MASS blue stars are more massive than red stars 0 The Sun is a MS star 0 The Sun burns hydrogen in its core 0 all MS stars burn hydrogen in their cores snuif l spngDE Laclmei ipage i The MassLuminosity Relation ioquot Brighl highmass sluts 4 i 0 r M x 9 uf 393 g 2 i02 E 3 j 3 i i 39 g Sun moss i MO E luminosin 1 13 3 4 1072 7 Dim lowrmuss slots i 0i i la Mass in solar massosl Mal I The VestRussell Theorem I926 Properties of ordinary stars are determined uniquely by mass and composition 0 MassComposition gt position in HR diagram 0 on MS star burning hydrogen 0 BUT star is voluntarily changing its composition 0 VR theorem demands 0 star must leave MS when hydrogen is exhausted 0 so stars must move in the HR diagram as they age 0 Stellar Evolution Life ExpectanCIes for Main Sequence Stars Mass x sun Lifetime yr 39 IO IO 39ll39 0 available fuel supply oc mass m39 390 o J L 5 80 million 0 rate of fuel consumption oc imgii 3 370 million 0 rate of consumption X lifetime total fuel consumed o g 5 2 393 b v 39 l l0 billion p so x llfetlme oc mass we see stars as If they 08 20 are li 39i fi 11quot o 0C rill xiii O or l39fet39me mass 39 quot39 0 Stars in the sky h ve different ages 39 combine with 7 0C massl to give 0 Which stars are young 0 Which are old W t 0c UN3 7 ms 0 How do they evolve M quot3 O l fi1iquotii 39r gt ri39iain tms101039Yr39X Msun along the l r iall i 0 main gt white dwarfs Massive Stars burn out faster 0 Ages needed of a bunch of stars to trace a grijellar lij39iie Astro 150 Spring 2005 Lecture 13 page 7 Key Objects Star Clusters 0 Associations 0 several dozen stars 0 IOIOO pc in diameter 0 lots of massive main sequence stars 0 Open Clusters ie Hyades Pleiades M67 O lOs of parsecs in diameter 0 IOO several thousand stars 0 found in MilkyWay disk ieOmega Cen M80 l0000 00000 stars l0 50 pc across found in the halo of the MilkyWay o Oen Clusters A Globular Cluster M l4 Astm Ian SpIng mua Lemme Ia page II mg Ian 5me 2mm Lemme Is 9212 HR CM diagram for an Association HR CM diagram for an Open Cluster I I I I I I I 2 2 0 0 Mv Mv 2 2 4 4 6 e I I I I I I Ir I As1yo 150 Spying 2005 Leduie 13 page 13 HR CM diagram for a Globular Cluster As1yo 150 Spying 2005 Leduie 13 page 14 Cluster CM Diagrams 0 Associations 0 nearly all stars on Main Sequence 0 includes 0 and B stars 0 Open Clusters O O and B stars are missing from Main Sequence 0 a few red giants 0 Globular Clusters 0 no main sequence 0 BA or F stars 0 many red giants and other stars 0 only lowmass stars remain on Main Sequence Remember M tms1010yrx Msun 3 As1yo 150 Spying 2005 Leduie 13 page 15 Type Mass x sun MS Lifetime yr 0 l0 l0 million A 3 370 million G l0 billion K 08 20 billion 0 0 stars in Associations 0 they re younger than l0 million years 0 MS A Stars in Open Clusters 0 older than l07 years and younger than 400 million years 0 O B stars have become red giants 0 MS G Stars in Globular Clusters 0 all stars more massive than G stars have become red giants 0 age l0 billion years As1yo 150 Spying 2005 Leduie 13 page 16 as a cluster ages 0 main sequence peels down 0 clusters do not change type as they age 0 most massive remaining MS star gives age of cluster llllilllllllllllllll 1yr l log me quot iiii iiii iiii Iiii Illll L l l l l l l I l I I I l l I I l l l l l I I l l 38 37 36 35 log Te m D Age of oldest clusters l2 l4 bllllon years Is this the age cf the Universe I With star clusters as our guide we can lnlnnslc bnghtncss o recreate life cycles of stars with different masses birth a middle age a old age a death 0 follow several generations of stars 0 trace history of the Universe from its creation to the distant future Sui cuium Reading cnaiierissemen iss Chavler Wi emnns l ii OBAFGKM lamest a timer mnemonic lur owcxw whuen are heiuenmesaeiomv iiaghgnyan imeiemeh Daml Drimsl Brie heinew oi last Lime HR Diagram Groups Stellar Mass Mam E333 re The Main Sequence Red Giants and White dwzrls 91m oi stars are on the Main Sequence most prominent stars are very rare but very luminous Determining stellar masses Binaryst rs Ke 0 Wed with seerszw law The Mossiummosiyreizhon The Mas Luminosity Relation ri mar emuaure DIEMFIEHEW muuuinh 4 ior main sequence stars Main sequence is a sequence in S Lars are more massive than red stars The Sun is a MS star 0 The Sun burns hydiogen in IE cone all MS stars burn hydrogen in their cores The Mas LumInOSIty Relailgh m WWW LAl i in l i m The VogtRussellTheorern 192 Properties of ordinary stars are determined mquely by mass and co posltlon 0 MassComposiLion rgt poslllon in HR diagram 0 on MSsiar burning hydrogen 0 BUT star is voluntarily changing ILS composition 0 VVR theorem demand 0 star must leave M3when hydrogen is exhausted 0 so stars must move in the HR diagram as mey age 0 Stellar Evolutionquot Life Expectancies for Main sequen E quotE F W 0 available fuel supply 0 mass 0 rate of fuel consumption 0 39 0 rate of consumption x lifetime total fuel consumed soifetime 0 mass llquot combine With IJD IIJOSIUj 0 mass4 to give tl 5 0 1M3 Tl 0 Massive Stars burn out faster 0 we see stars as if they are frozen in time 0 Stars in the sky have different agg 0 Which stars are young 0 Which are old 0 How do they evolve 0 red giants v main sequence 0 along the main sequence 0 main sequence 39 white dwarfs 0 Ages needed of a bunch of stars to trace a stellar life cycle m is mm um um Key Objects Star Clusters 0 Associations 0 several dozen stars 0 10100 pc In diameter 0 lots of massive main sequence stars 0 Open Clusters ieHyadesPleiadesM67 0 10s of parsecs in diameter 0 100 several thousand stars 0 found in MilkyWay disk 0 39 39 39 5 ieOmegaCenM80 0 10000 100000 stars 0 10 50 pc across 0 found in thequothalo of the MilkyWay HR 3er dlauram for a Globular I Cluster C M Diacl rams 0 Asso ns 0 nearly all stars on Mam Sequence 0 Includes 0 and B stars 0 Qpen Clusters o o and B stars are mlsslng from Mam Sequence 0 a lew red glam 0 Globular Clusters mam sequence 0 BAor F stars 0 many red glam and other stars 0 only lowmass stars remam on Mam Sequence my Remember hs WW m K mu 0 0 stars in Assoc ns 0 they re younger than 10 million years 0 MS A Stars in Open Clusters 0 older than 107 years and younger than 400 mllllon years 0 O B stars have become red glams 0 MS G Stars in Globular Clusters 0 all stars more masslve than G stars have become ned glams 0 age 10 bllllon years as a cluster age39 0 main sequence peels downquot gmlmmmlmange weanlewa 0 most massive remaining MS star gives age of cluster intrinsic brightness yei iew Siai eeieiii Age of oldest clusters 12 1 4 billion years Is this the age of the Universe I With star clusters as our guidewe can o recreate iiie cycles oi stars WILh diiierent masses bl Lh a middle age a old age a death o follow several generations oi stars 0 trace history of the Universe from its creation to the distant future Reading Chapter 6 section 65 apter l6 sections l6l l65 OBAFGKM Contest a better mnemonic for OBAFGKM I written or email entries due thisThursday February 23 I judging by an independent panel I rizes Asa if SpngDE L mi inEg 1 Brief review of last time Distances and the HR Diagram Distance as a pivotal quantity Trigonometric Parallax for measuring distances I distance to nearby stars by triangulation I distance in parsecs lparallax arc seconds I from ground or from space Stellar Motions I Proper motion and tangential velocity I Radial Velocity via the Doppler Effect Statistical Parallax motion of the sun for a bigger baseline Uses of the Doppler Effect The HertZSDrunERussell HR Diagram I classi cation tool luminosity plotted vs temperature Asa if SpngDE L mi inEg 2 A Census of the Stars I Observed Luminosities L 00000 gtgt 00000 X L sun su n I Observed Temperatures 2000K 200000K I Classification stars of a given spectral type temperature can have vastly different luminosities ranging over factors of several thousand I Need to classify stars by spectral type and luminosity I9I4 The Hertzsprung Russell Diagram Asa if SpngDE L mi spectral type as X luminosity as Y spectral type 0 B A F K M 106 O 104 7 I I O 102 I I39II L I I I g 1 I L III S 10392 104 7 0 L 104 l l l 20000 10000 5000 lt Temperature K inEg a The HR Diagram 3 device to cla sl xpllgiiar W A by spectral type Le T or color and Luminosity I Radius on the HR Diagram ll starsatsame statsatsame HigherT IsmallerR HigherL BiggerR I biggest stars upper righthand corner of HR Diagram Asa lE SpngDE L ml lZpEg 5 Radius on the HR Diagram ULsun spectral type A l 10000 lt Temperature K l 20000 5000 Features on the HR Diagram 0 The Main Sequence 0 diagonal band 0 90 of all stars are Main Sequence stars 0 The Giants 0 upper right high L lowT gt huge size 00 Rsu 0 White Dwarfs 0 lower left low L high T gt tiny size 00l Rsu Asa lE SpngDE L ml lZpEg 6 n and more and less n Asa lE SpngDE L ml lng 7 Features on the HR Diagram ULsun spectral type A F G K M 10G 104 10392 10quot Sequence RedGiants 0 o 0 TheMa in 10000 5000 lt TemperatureK 20000 An HR diagram for all stars with Hi arcos s ace arallaxes distance limited brightness limited Asa lE SpngDE L ml lZpEg An HR diagram for the brightest stars in the slgx quot HEDEHANT 1000D 39 Dene REGiUN el g 39 eraxfelelgeusa F Armurus 39 19 9 E 2 a E 1 u Leniaun 397 5 Sun quot I S MAIN E SEQUENCE 391 RE cum 7 v01 R 0001 V 39 I 30000 10000 6000 3000 Surface zemperaiwe K we Asa if SpngDE L mi inEg 9 Main Sequence stars are the most numerous BUT The most prominent stars in our sky are the rare but luminous blue main sequence giants and supergiants 0 Why such variety 0 What makes stars so different from one another 0 What are we missing MASS Measuring Stellar Masses Binary SW W W 0 Kepler s Third Law for binary stars d3 M2 7 M1M2 P2 orbital period yrs 0 The See Saw Law centerofmass a a quot1 M2 d1 d1 d2 0 sum and ratio of masses allows determination of the individual masses of each star Types of binary stars 0 Visual Asa if SpngDE L mi ing H 0 widely separated l0l00 auand more 0 knowdd2 d2dl P sometimes Spectroscopic 0 spectral lines show periodic Doppler shifts 0 too close to see individual stars know dZdl from velocities P Eclipsing 0 brightness variations as stars eclipse one another 0 know P shapes of stars light distribution Eclipsing spectroscopic rare 0 provide dd2 dZdl P and so masses 0 radii from eclipses and orbital velocities Astrometric 0 stars that wiggle 0 bright star orbiting an unseen com anion 0 provides d2 P Wmquot mean w Castor a visual binary Asa if SpngDE L mi ing lt2 m ISDSVInEQDDE L w mag I 0 Double line spectroscopic binary A doublelined Spectroscopic Binary star 0 Eclipsing binary We 50 mm We 500 ngm We sen llglll Wt see qulVl Imm mm lmm Ill ml H mm mm My mm A A and B some M A A and E 3 a 1 c 5 apparent mgnmess IImc 4 m ISDSVInEQDDE L w mag u 0 more than 50 of stars are in binary or multiple systems 0 BUT only a few dozen can be used to measure accurate stellar masses 0 Key Observation Stars with the same mass have the same spectral type on the Main Sequence Key Observation m ISDSVInEQDDE L w mag I5 Stars with the same mass have the same spectral type on the Main Sequence spectral type A F 6 O B 1 ougomsun 104quot 00 o 102 f39 g 1 5Msun I i 102 104 1043 l 20 000 lt Temperature K 1 0000 5000 Properties of Main Sequence Starssquot We 2313233quot Ll39sun MMsun RRsun Example I 260000 20 I 0 Rigel I 00000 60 3 25 Vega I 000000 I I I Sun Capella 5000000 006 04 06 33quotquot 0 Lower mass limit of Main Sequence 008 Msun 0 stars less massive don t get hot enough to burn hydrogen 0 Upper mass limit 200 Msun o if M gt IOO M violently unstable sun Astr 150 Spr1n92005 L tur 12 pag 1 The MassLuminosity Relation tronger ig er pressure raVIty needed to maintain HSE Main Seuence Extremes 39 otternteror emperature Morerapid energy 0 Eddington I926 KeckINIRC smcsmnc Hm L o M4 for main sequence stars Cf212 02 l V 0 Main sequence is a sequence in MASS blue stars are more massive than red stars 0 The Sun is a MS star 1 39 apiA 39sW f EEKiEi oazl 0 The Sun burns hydrogen in its core git39ol Nebula and Massive Star lST 39 NICMOS NASA ESA and H Euuy MPE 42 43 5T sci CPO 0 Fine lUl39JLN arm HAS 0 all MS stars burn hydrogen in their cores Am 159 Spring2005 L m 12 pag 19 Astr 150 Spring2005 L tur 12 pag 20 The MaSSLumanSIt REIatlon The VogtRussell Theorem I926 Properties of ordinary stars are 10 Brigmrhighmsm determined uniguelx by mass and 7 39 composition L 10L LM4 e 5 0 MassComposition gt position in HR diagram 2 107 7 if 0 on MS star burning hydrogen 1 0 BUT star is voluntarin changing its composition quot mliifiillff 0 VR theorem demands a 3904 l 0 star must leave MS when hydrogen is exhausted 7 3 Dim lowrmuss Sims 01 1 110 0 so stars must move in the HR diagram as they age I Moss in solar masses Mel F 0 Stellar Evolution rzzi emnn 22 72 Reading cm cm Pimp15 aWrUIai vnurm mismmayiaig on iasl dymmum rim Exam Wednes dyi Denying is a mi as 2 i2 0 ACUVe Galatllc 3 o Cenlml Black Hole as accrEUon 70 2 5 rz i emnn micmiwzaimm zai Brie review oi izst time quasars and ACLIVe Gzlzcuc Nuclel o Quaszrs iarge redshiit r iarge mum right 7 high mmmosity smaH siZE from rapid Variabihty mnnyspecm spectrai iirie components Nuclei an Energy Source Sumpermassive accretmg BLACK HOLE mpressiori nosit 0 Need quotonly HOsunsyezr lorMi L y C latlons in L E Varlablllty yflow Var size of BH 3x1069 km 101000llghtsecondslt small SIZE 0 Other phenomena rooted Illal iAccretlon Disk i i i gm m momh 9 Reign Specxium M Gas Disk Acliva Gaiaxy MS7 Muhblu Swen m Un fied Model of AGNs lLs 39 A alter of Inchnazion Edgeron see dlsk ed e delo gzllees Seyfert 0 Tllted see ho dlsk Quasar o Faceron borerslght on BH Os creame m we mam 3517 l lawEr lei257 Way haan black me auhElr We Duesamnllymnllnua m Duallgalaxles ncludmg DuerlKY c2nlers7 a Galaxy NGC 416l Core l Huhhle Suace39lzlsscnlw mam usr l wmz Galaxy Mu Nucleus ga uSSFCl r amalwmlmm Hubble space Telempe rum sadL11 l Dark Matter within qalaxiesinm m39quot F72 l o quotRotauon curve glues rotatlon speed ma spearoseo Rolauon rate ol starsclouds glues mass wllhln me orbll 0 Splral Galaxles r matter extends well beyond Vlslble disks 0 Elllptlcal Galaxles r blg ML ratlo ea IS dark o 93 of L mer Scale Structure 0 Ga lazy Clusters o ExampleThe Local Group N 25 We l Mun ExampleTheVIrgo Cluster mm 0 Componenu cDuenUaldummanl terminal galaxy mum his or linersfully gm Mass Mcluster gt 10 x Mms39ble imm velocitiesJensIng in the Ur VefS quotquot l9 AnglerAustralian ansemaer U DlslnntGilnxy mm m Clnsmah n 2215 mm 5pm qunllc mle Galaxy Interactions 0 Envlronments of galaxies splralslo nd m spa e groups or Isolation ellipticals dominate crow 39 p galaxl I 0 We see my examples of Interacting colliding es r e clusters 0 stars almost nevercolll e 0 gas clouds me eracmnducmg stariormatlon o udaldlstomons 0 Elliptical Galaxies form when spiral or other types of galaxies colli collisions smp andor use up gas 0 OOIIISIO s may quotleed the monsterquot Am isn mam um um Ies are not dlslrlbuled randomly Galaxy clusters not dlslrlbuled ra d ly SUPERCLUSTERS 0 filamentary structures 0 bubblelike frothy structure 0 walls and voids 0 Huge structures like quotThe GreatWall39 0170x60x5Mpc 39 1X 0 Some questions 0 Is bubble structure a vestige of early phases of the Universe 0 How do you make galaxies in an expanding Universe Am isn mam um 2mm Sample largescale survey 1000 Puhlu Lecture 3mquot GM Exnlammylhe Elegant Ummm mummy NonEmber 3 am Sun Room Stellar Populations in the Milky Way Reamng ChaVIEr w Exam 2 grades Dusla memmwnmmnaammwa mum quot 39 3W5 39quot 9 D39sk covow o masslve stars open clusters Brlel revlew 0 last We the ISM and our Galaxy the Milky Way orb W39lh39quot d39Sk 039 SB39ZXY 39m I abundance same as Sun or more lmemlellerbsorPuoquot quot65 Population 39 Stars In the Halo InterstellermmIc Absorption Lme Clouds ll Reglons planetary nebulae and H1 21 cm very 390 quot ammmame o Molecules aquot Dun 0 orbIB way out olgalacuc plane lR Rama 0 low mass stars globular cluster 1 x scattermgamorptlon blue llgm reflected redderllgm ransmltted P0 mans as clues to the formation of the M W lnterstellarReddemng Q Raul 1m vents uranium aamrmamn Inlhe Mw The SW Gas Star cycle I a cnllzrlse mlherlzw o The Milky ay a m rmmnmlzl luncnmm menzl pm 53 rmrermzmwmmu HIGH MEIALS szsmmm 1mm dmns m may sans W G laxy menslons sh2p2 posltlon 01012 Sun ow do we know n ls a splral galaxy7 alact c R o dl enenllzl mlauon Inner pans mtate aster than outer paru o orbital period olSun 230000000 years the P b th tr t Ith GI aquot l w mg 95 Home a9 80 m the structure of the Milk Wa 0 Globular clustersspherlcal halo of old Stars Sun ls 20 galacnc years old o distance 0 MW center 3500 pc o Mass of Milky Way via Kepler39s Laws 10 MWquot nmasslnllnwslmhl am mam dlsznm dlsznm o DARK MATTER 90 of galaxy mass 0 M am am m Am isn mam um w wave a Am isn mam um w wave 5 Tracinq the structure of the Milkv Wav 0 Young OB Stars delineate spiral arms 0 most luminous stars around 0 dust blocks more distant ones 0 we live In thequotOrionArm lllcll VolI Dquot 220 200 ISO 60 HO W E E Pemiisami E 0 OviunCygnus arm 399 39 I g a 90 i 70 so Tracinq the structure of the Milkv Wav 0 HI 21 cm and Molecular Cloud maps 0 Each lineof sight has many clouds at different distances 0 Use differential rotation of galaxy to estimate 0 cloud distance using cloud radial velocity Am isn mam um w mu Tracing the structure of the Milk Wa 0 HI 21cm and Molecular Cloud maps 0 IR Radio mapping 0 differential rotation to get distances Sun a Oulicalleaiuves Mnluculucluud ii in ion Fla 9 smmnwmpige fez 39 Parseusarm Oilnnlacalarm 39 QA 39 Emmi f eg r s jg Sumabig we 31 g W39MM a 39 gt r 3 v SaginarluS r Centaurusarm A M1 am y I b is i l l6 i s 0 1 General I neulml hyamgen and older slum kpc What keeps spiral galaxies spira7 mumm piral Densit Waves Humm Age 039 Gal 0 Arms must be xed panems through which 12 h s and gas move on year so gszy rotzuons dl erenllzl notationer would have wound up youngest stars lound In arms 0 5 51 599 a o Arms must be W through which long ago a 0 LOCaIIZed density Increase 7gt enhanced star formauon Back to the dark matter39 issue Mass of Milky Way via Kepler39s Laws 10 MWquot dlsznm