New User Special Price Expires in

Let's log you in.

Sign in with Facebook


Don't have a StudySoup account? Create one here!


Create a StudySoup account

Be part of our community, it's free to join!

Sign up with Facebook


Create your account
By creating an account you agree to StudySoup's terms and conditions and privacy policy

Already have a StudySoup account? Login here


by: Mylene Russel


Marketplace > Oregon State University > Physics 2 > PH 104 > DESCRIPTIVE ASTRONOMY
Mylene Russel
GPA 4.0

J. Ketter

Almost Ready


These notes were just uploaded, and will be ready to view shortly.

Purchase these notes here, or revisit this page.

Either way, we'll remind you when they're ready :)

Preview These Notes for FREE

Get a free preview of these Notes, just enter your email below.

Unlock Preview
Unlock Preview

Preview these materials now for free

Why put in your email? Get access to more of this material and other relevant free materials for your school

View Preview

About this Document

J. Ketter
Class Notes
25 ?




Popular in Course

Popular in Physics 2

This 157 page Class Notes was uploaded by Mylene Russel on Monday October 19, 2015. The Class Notes belongs to PH 104 at Oregon State University taught by J. Ketter in Fall. Since its upload, it has received 23 views. For similar materials see /class/224527/ph-104-oregon-state-university in Physics 2 at Oregon State University.




Report this Material


What is Karma?


Karma is the currency of StudySoup.

You can buy or earn more Karma at anytime and redeem it for class notes, study guides, flashcards, and more!

Date Created: 10/19/15
English Units Distance Metric Units 12 divisions 1 inch 10 millimeters l centimeter 12 inches 1 foot 100 cm 1 meter 3 feet 1 yard 1000 m l kilometer 55 yards 1 rod 1000 milligrams 1 gram 4 rods 1 chain 1000 g l kilogram 10 chains l furlong 8 furlongs 1 mile 3 miles l league 00000001 meters is difficult to read and write too many zeros Use scientific notation to simp i y 00000001 m lgtlt10397 W Move the decimal place seven places to the left to determine the powerexponent of ten 7 Moving it to the le makes the power negative 7 Moving it to the right makes the power positive 39 ti c Notation Commonly used prefixes Scienti c Number Wm Pre x Abbreviation 1000000000 1x109 giga G 1000000 1x106 mega M 1000 1x103 kilo k 001 1x104 centi c 0001 1x103 milli m 0000001 1x106 micro n 0000000001 1x103 nano n The Light Year 1y Distance light travels in 1 year 1 Earth year Equivalent to a lookback time it s how far back in time we are seeing Example Proxima Centauri is 41 ly away The light we see from it today left the star 41 years ago We see it as it was 41 years ago The Parsec pc 7 PARallax SECond 7 Distance to a body whose parallax motion covers 1 second of arc 7 lpc326ly 5mm x mm 1 M Dam mans 3hr 1 ligher i I AM my mam i rumdin Ism may 1 5 12 my swam smv mu m a an m 9mm indunmknukm i 5 6 9mm The Scientific Method The Scientific Method is the procedure scientists use to o o construct their ideas about how 39 A NIOCiel IS a deSCI IPtIOH nature everything works The of physical phenomena hope is to come up with a that we feel matches Sc1ent1 c TheoryModelLaw W611 with reality rn Sbi39alslemeasurable things 39 The CeleStial Sphere Explains observable things 39 UniVefsal GTEWitatiOlil Must be testable Electron Orbitals Must be disprovable Predictive s v 239 Principle of Uniformity The Laws of Science are the same everywhere in the universe The Laws of Science are the same everywhen in time If these aren t so then any model of the universe is possible and perhaps equally valid The Nature of Matter Prolon Prolon Nuclei 9 j Nucleus n 39 Neutron Neutron a I r Electron quotcloudquot Electrons Protons positively charged and neutrons uncharged make up the nucleus at the center of an atom Electrons negatively charged particles are found relatively far from the nucleus 7 If the nucleus were the size of a grape the electrons would orbit at a distance about the length of a football eld 7 Most solid matter then is made up of mostly empty space Fundamental Forces in Nature 0 Gravitational Force Strong Force FQrce between ObleCtS Force that holds atomic Wlth maSS nuclei together In nite in range but Very Short range 1015 weakens with distance meters Weakest of all forces Weak Force EleCtromagnetic Force Force responsible for Force between charged radioactive decay bOdieS Very short range 103918 Like charges repel meters In nite in range but Really related to weakens with distance electromagnetic force The description of the universe and its contents using elementary particles is called The Standard Model Elementary Particles Smaller particles known as quarks make up protons and neutrons Up quarks Down quarks Up and Down are just labels Other kinds of quarks have names like strange and charm and again are just labels if 3 l Astronoth for ancient peoples A sense of wonder The night sky is an amazing and beautiful thing to look at and think about Navigation Agriculture when s the rain coming Calendar Curiosity Superstition Guidance Connection to gods Time e Sagiiluvw X As the Earth revolves around orbits the Sun the Sun appears to move through 13 constellations on a belt around the celestial sphere called the ecliptic When the sun in the sky is in fron of a particular constellation we say that the Sun is in that constellation As this motion repeats itself after one year it is called the Sun s annual motion m J mm w mm 1 may mumquot mm m m im pain 3m m Jm Mn a mm mm sq um xw v N mnuul equam m EMT The Ecliptic The ecliptic belt on the celestial sphere is tipped relative to the celestial equator due to the 2350 inclination of the Earth s rotational axis In June the Sun appears north of the celestial equator In December the Sun appears south of the celestial equator Twice a year the sun appears on the celestial equator 7 these times are called the equinoxes The Earth s inclination is Ultimately 1110 Pole responsible for the change in seasons 7 In June the 7 Northern September Hemisphere is tilted 0 Common Myths towards the sun 7 Summers are warmer because the Earth is closer to the Sun than in Winter I Actually the opposite is true in Northern Hemisphere 7 The tilt of the Earth s axis brings the Northern Hemisphere closer to the Sun in Summer and farther from the Sun in Winter creating the seasons I Geometry is true but this accounts for only a minute Emotion of the extm heating in summer 7 In December the Northern Hemisphere is tilted away from the Sun This tilt of the Earth has two important effects 7 In Summer the Sun spends more time above the horizon 7 days are longer resulting in more heati hunk Pole 1 A n n Nnrlh P39l 39 7 In Summer light from the Sun strikes the ground more directly concentrating the h mm H m A Sun s energy Equulul Summers are therefore warm er than Winters w wwer w m ppm mmmumm mm m m Earth s rotation axis swings In new position To Polaris Toward Vega 9 9 i lt Nonh Pole now I quot Spinmn and precessing lop The Earth spins about its axis like a top but the Sun s gravity adds a pull that causes it to wobble This wobble means the aXis of the Earth is rotating or precessing with a 26000 year period 1 2 3 no Precessionl Because of this precession Polaris the North Star will not always be The North Star 6000 years ago the North Star was Thuban a star in the constellation Draco In 12000 years the Earth s aXis will point toward Vega a bright star in Lyra The Sun The Sun is a huge ball of gas at the center of our solar system 7 A million Earths would t inside it 7 Releases the equivalent of 100 billion atomic bombs every second Exists thanks to a delicate balance of gravity and pressure A delicate balance The immense mass of the Sun generates a huge gravitational force 7 Gravity pulls all of the Sun s matter toward its center 7 This crushing force produces a high temperature and pressure on the interior of the Sun This balance of gravity and pressure will allow a star like the sun to live for billions of years The Solar Interior m m m m m u m u n 15015 mum Temperu ure mm mum1mm 9 mum 5 mHh on 3 ml m A mum 39oacsosmm CZOAD DEICRV The Photosphere The photosphere is the Visible surface of our star 7 Not really a surface as the Sun is gaseous throughout 7 Photosphere is only 500 km thick 7 Average temperature is 5780 K i p The Surface of the Sun 0 Most of the features we can see are located in the photosphere Regions of rising gas that look like bubbles are called granules and represent the transport of energy from deeper in the Sun to its atmosphere Sunspots are found in the photosphere 7 Cooler and dimmer than their surroundings but still very hot and bright Energry Transport in the Sun Just below the photosphere is the convection zone 7 Energy is transported from deeper in the Sun by convection in patterns similar to those found in a pot of boiling water hot gas rises dumps its energy into the photosphere and then cooler sinks back down Energy in the convection zone comes from the radiative zone 7 Energy from the core is transported outward by radiation 7 the transfer of photons 7 Takes more than 10 million years for a single photon to escape the Sun l The Solar Atmosphere Regions of the Sun above the photosphere are called the Sun s atmosphere Just above the photosphere lies the chromosph ere Above the chromosphere is the corona 7 Usually invisible but can be seen during 7 Extremely high temperatures solar eclipses more than 1 million K 7 Spicules tall thin 7 Rapidly expanding gas forms the columns of hot gas solar wind 15 million tonssec A Very Active Star The surface and atmosphere of the Sun are extremely active Solar Wind streams out of coronal holes regions of low magnetic field Active regions send arcs of plasma shooting from the surface These are regions of high magnetic eld Coronal mass ejections send large quantities of mass out into space Solar ares release energy and hot gas into space Stars like the Sun can be seen as having a kind of thermostat 7 Gravity pulls inward pressure pushes outward 7 If temperature begins to fall pressure decreases and gravity pulls more mass toward the center 7 This inwardfalling mass increases the temperature and pressure restoring balance l Ihe Solar Thermostat rum o 11145me H mm it w m munmmmm amquot The outwad pvessule we balances the inward qromuhonul lorce eve39ywhsre nside the Sun Surface of Sun Hydrosiulic eqummum Carter of Sun The Ideal Gas Law cosylamenngthchme m Pmi mrnundfvruprvduniw mm Gus coal Gus I39Iul Atoms move slowly Aloms move rapidly Pressure small Pressure large Pressure Constant x Temperature gtlt Density H is l y How dd we know all of this Naturally we ve never seen the inside of the Sun 7 Computer models suggest the layered structure we ve discussed 7 We can probe the 1nterlor us1ng helioseismology the study of sunquakes The Sun s Energy The Sun s energy comes from nuclear fusion the merging of hydrogen nuclei into helium Each fusion reaction releases only a little bit of energy but it happens a lot A helium nucleus has less mass than the four protons hydrogen nuclei that fuse to create it This difference in mass is converted into energy E mch 9quot v l I r In the core of the Sun the temperature exceeds 15 million K and the pressure is very high High temperatures imply that the nuclei in the core are moving very fast and the high pressure is pushing them together The high speeds of the nuclei allow them to collide and fuse via the protonproton chain Temperature and Pressure Are the Key nnr Low temperature gmd a lei move slowly on eleclric lame repels Ihem and pus es lhem aparl Nu luslon High temperalure 7 gt Nuclei move laslel and eledrical Force yepeumg lhem is overwhelmed They mum and fuse 4 2H 3 11 JHD The ProtonProton Chain imghl cm XGm lllll39nmp m395 Inc l39rmllmml requml rm Icpnxlnumn m dnulm H Mush c mmomnm WWW m m Wm WWW w WM AZ neulvino v O gt 0 2H H position 9 H gamma ray 7 Neutron Proton Neutrinos Another product besides energy of the proton proton chain are neutrinos 7 Very low mass very high energy particle 7 Passes through matter very easily and so is hard to detect 7 Neutrino measurements on Earth con rm our models of fusion in the Sun s core Sunspots Sunspots are highly localized cool regions in the photosphere of the l h 3 Sun w Discovered by Galileo Can be many times larger than the Earth They contain intense magnetic fields as evidenced by the Zeeman effect i A Sunspot s Magnetic Field Hie MchMmi Cnn copyright 0 m M Magnetic field mm mm mm furrepmduclmn or The intense magnetic elds found in sunspots suppress particle motion Solar ions cannot leave these regions of high magnetic eld and the eld lines are frozen to the plasma This trapped plasma keeps hot material from i W Charged surfacing below the sunspot keeping it cool particle Particles spiral around the field lines Fields have their footpoints in sunspots i the photosphere These loops are relatively unstable and can release vast quantities of plasma into space very quickly Prominences are large loops of glowing solar plasma trapped by magnetic elds Coronal Mass Ej ections Prominences Cooling gas trapped in magnetic field Magnetic field Solar Flares Solar ares are huge eruptions of hot gas and radiation in the photosphere Can damage satellites spacecraft and humans in space The study of coronal mass ejections and solar ares is called space weather it A Coronal Mass Ejection The Aurora When CME material reaches the Earth it interacts with the Earth s magnetic eld and collides with ionospheric particles The collision excites ionospheric oxygen which causes it to emit photons We see these emitted photons as the aurora or Northern and Southern Lights The Solar Cycle Cupynyuommcanml Cnmpnmzl bc Permission requirgd furrepmduc nn min 200 lBG 150 g MO E 120 i too Z w 40 20 lB M W70 IBM 1390 W00 W10 WZO 930 WAG W50 I960 W70 V980 W90 2000 2010 The number of sunspots seen Around 55 years after Solar increases and decreases Maxlmum the SUHSPOt number periodically 1s at 1ts lowest level Th1s1s called Solar Minimum Solar activity CMEs ares etc peaks with the sunspot number Every 11 years or so the sunspot number peaks This is called Solar Maximum un s Sun equator PP39OX equator rotate once Appro d o 30 days 00 a o rotate once 5 Day 1 Day 5 0 Different parts of the sun rotate at different speeds Equator rotates faster than the poles Solar magnetic fields get twisted as time goes on The Babcock Cycle NE 1 quot l Suhswfuca magmatic Viald Coils duvalop kink Ihul break I now in to Waugh ma mince aunder Minimum Very few sunspots were recorded between 1645 and 1725 This is called the Maunder Minimum Corresponds to relatively lower temperatures here on Earth a little ice age The reason for the Maunder Minimum and its effect on climate are still unknown Copyrigth m Mmmw xll Trympnnies In reminder manned for mpmducnwn ordlsplay zoo Muund r minimum 1550 woo I750 150C 1550 I900 wso Year g 50 3 I00 5 250 2000 eightlessness No or little gravity Possible if far enough out in space A state of freefall How so 0 Standing on a scale in an elevator Accelerating upward Accelerating downward The cable breaks A state of freefall is equivalent to a state of weightlessness Kwva I Newton s Thought Experiment Imagine a cannon on top of a mountain that res a cannonball parallel to the ground The cannonball leaves the cannon and is pulled toward the ground by gravity on and Gravity If the ball leaves the cannon with a low velocity it falls to the ground near the mountain If the cannonball has a higher velocity it falls farther from the mountain quot eightlessness WPIHQMD WWW Nu Newton s Thought Experiment Continued What if the cannonball is traveling so fast that for every foot it falls the Earth curves away from the cannonball by one foot The cannonball will be forever falling and never landing The cannonball will be in orbit Being in orbit is being in a state of freefall Astronauts on the space shuttle in orbit are in freefall and are thus in a state of weightlessness Has to be otherwise the spacecraft wouldn t stay in orbit At the altitude of the space shuttle in orbit for example the strength of gravity is 90 of that on the surface of earth The same cannonball explanation is valid for every planet moon comet asteroid satellite in orbit around some other body Even in a state of weightlessness an object STILL HAS MASS Mass is a measure of the amount of stuff there is in an object Mass is not a measure of how much space something takes up That s volume Mass is a measure of the amount of inertia an object has Mass doesn t depend on location Mass is measured with a balance Units grams kilograms slugs Weight is a measure of the gravitational force on an object It varies depending on the planet or moon that you are on Weight is measured with a spring scale Units lbs newtons tons Every mass exerts a force of attraction on every other mass The strength of the force is proportional to the product of the masses divided by the square of the distance between Fvairy 6372M their centers of mass 7 Simply put everything pulls on everything else Thls 1s true everywhere and for all objects 7 The Sun and the planets exert a gravitational force on each other 7 Larger masses have larger gravity 7 Objects close together pull more on each other than objects farther aparp 7 You exert a gravitational force on other people in the room urface Gravity Objects 0n the Moon weigh less than objects on Earth This is because surface gravity is less 7 The Moon has less mass than the Earth so the gravitational force is less We use the letter g to stand for the acceleration of a body in freefall due to gravity Fgravity Weight mg On Earth g 98 ms2 g on the Moon is around 16 as much as on the Earth Origin of Tides 390 wing all he Mc rawHill 39om mnies Inc Permission re un39ed for reproduction or n ts lav Gravitational force of the Moon acting at different pcinls on Earth Tidal bulges resulting as oceans flow moved by Ihe tidal force The Moon exerts a gravitational force on the Earth and the water in the oceans The effect of the various forces acting together causes the water to create tidal bulges both beneath the Moon and on the opposite side of the Earth from the Moon and Low Tides Nmmx As the Earth rotates m beneath the Moon the water on the surface of the Earth experiences high and low tides 5 mm mar I Maw gt High Iid H gh Me 2 km rum v5 Moan gt low tide httpwwwsfgate comgetoutsidel 996juntides html a The Sun Also Effects the Tides Tidal tome horn the Sun Earth Neup mes Spring Vida The Sun is much more massive than the Moon so one might think it would create far larger tides However the Sun is much farther away so its tidal forces are smaller but still noticeable When the Sun and the Moon line up higher tides call spring tides are formed When the Sun and the Moon are at right angles to each other smaller neap tides result Not Energy Conservation but on From MW cm whm anybadq tad5 GAKdeA 511T ereswm wl gammaam 701 H ReggdumunnngumamaMenum F www GennnnStnck com How car l39oons ar helpin The environment AWARENTLY HE S NOT LAZY aueT DOlNG HIS BlT TO CONEEEVE ENE Y servation of Energy The energy in a closed system may change form but the total amount of energy does not change as a result of any process 0 Energy can be neither created nor destroyed but only changed in form 0 Technically it s the law of conservation of mass energy Kinetic Energy Kinetic Energy is the energy of motion Both mass m and speed V contribute to kinetic energy 1 EKEmgtltV2 Kinetic energy Imagine catching a thrown ball If the ball is thrown gently with low speed it hits your hand with very little pain If the ball is thrown very hard at high speed it hurts to catch Thermal energy I 239 T Thermal Energy Thermal energy is the energy associated With heat It is the energy of the random motion of individual atoms or molecules Within an obj ect What you perceive as heat on a stovetop is the energy of the individual atoms in the heating element transferring to your finger Really it s a form of kinetic energy Potential Energy Potential energy You can think of potential energy as stored energy 7 quot 7e 77 Better it s energy due to position Gravitational potential energy is the energy an object has due to its position in a gravitational field Potential energy is released When the object is put into motion or allowed to fall Forms chemical electrical elastic gravitational of Forms of Energy COWergo 0 PO39gnllol energy A bowling ball is li ed from the oor to kinetic and thermal energy Onto a a e Converts chemical energy in your muscles into potential energy of the ball 7 The ball is allowed to roll off the table As the ball accelerates downward towardthe oor gravitational potential 39 o 39netjc energy 7 When the ball hits the oor it makes a sound and the oor trernbles Kinetic energy of the ball is converted e in the oor and ball get knocked around y the impact K i fngular Momentum Linear momentum p m X V If no external forces are acting on an object then its linear momentum is conserved Angular momentum is the rotational equivalent of linear momentum Can be expressed mathematically as the product of the object s mass rotational velocity and radius If no external forces torques are acting on an object then its angular momentum is conserved or a constant LmgtltVgtltrconstant 7 6f Angular Momentum Since angular momentum is W quotngmgig rxggg39atgtz39v r ti za r conserved if either the mass l H size or speed of a spinning object changes the other V values must change to maintain the same value of momentum 7 As a spinning gure skater pulls her arms inward she changes her value of r in l gtl angular momentum H V 7 Mass cannot increase so her 4 V J rotational speed must increase y v to malnta1n a constant angular momentum Works for stars planets orbiting the Sun and satellites orbiting the Earth etc l i Reminder of a Star s Internal Processes t The balance of forces in the interior of a star is delicate though stable for millions or billions of years Principles Govern g Ihe snuuure of a Main Sequeme Slur slnrlognlhai v alums my rgninsi gm n m lmlme lwdmm Emma I39llgl39rsmrsmlllrelnlar39smm 9quot a 3 7 A star acts like it has a K25 cal59 mllwlm colemmm 39 thermostat um awe as the we lvmlncsll y lsmllgm k m mammalle I W l Hydlogell rum um hellulll m ml 7 If internal temperature decreases internal pressure decreases and the star collapses a little raising the temperature 5m mmlly st all a We nglmlus slur leqlue move was lo Nippon llw will mm 2mm pressure ls prcduced Ly l ghar lempemllmi nglw lempvqlule Maine may lumlncs 39y nghz llm ands la balm hul usage realm luel l mam a lllglrmun w burlli glimmer than u lawns m When hydrogen in the core is exhausted the thermostat breaks m Evolution to red giant phase Towngmi II mama ompamey Inc Pwnixxmn rzquired for reproduction mm a A E g 4gt me 39 mm Shell fusion increases inner pressure The star is expands and cools luminosity increases while its temperature decreases Position on the HR diagram shifts up and to the righ Luminosiiy we 00000 Evolutionary tracks of giant stars ZeroAg main sequence These are the paths for stars that have ended core fusion and begun shell fusion End of main sequeme fusion 10000 Temperature K Helium Fusion Ha 100000000 K 10000000 x Normally the core of a star is The core of a red giant star can not hot enough to fuse helium reach very high temperatures 7 Electrostatic repulsion of 7 Ifthe temperature is high the two charged nuclei enough 39 100000000 K keeps them apart helium fusion begins A temporary new lease on life The triplealpha process provides a new energy source for giant stars Temperatures increases temporarily until the helium runs out The stars cool and then expand once again The end is near 10000 kmpemh no Variable Stars Variable stars change their brightness overtime dimming and brightening again To characterize the variability of a star scientists measure the brightness and plot it as a function of time This is a light curve Different types Irregular Variable Nova death T Tauri stars birth Palsating Variable Periodic changes in brightness 4 Evighmess a Light Curves row a the came Comm m yawn mm m whim up RR Lyme Vuriublo Mira Variable a Period A ma f gt3 gt1 angmms O 5 O 75 1 me days a Capheid vuliuble HiPanod Brighlness 4 400 800 1200 Time days 4 Nanvariuble 5 ID We days 7 a 400 800 1200 Me days 7 D Yellow Giants and Pulsating Stars If you plot the positions of variable stars on the HR diagram many of them fall in the instability strip 7 Most have surface temperatures of 5000K so appear yellow 7 Most are giants Yellow Giants 7 Instability comes from partial absorption of radiation in the interior of the star Helium absorbs radiation and the outer layers of the star get pushed away from core As the star expands the density decreases letting photons escape Outer layers head back inward toward core Repeat 7 RR Lyrae and Cepheid variables are useful for nding distances to the stars as the star s period is proportional to its luminosity Periods of Variable Stars Luminosil y gt In V display Mira variables 2 weeks 1 year RR Lyme variables Period approx day Pulsaling while dwarfs Period approx few minutes lt Temperulure A A Fluctuating Balance opyngm a nu McanJhll 39nmpamex In A elmlssmn required fnrreproduc on m may Radmnon Rudxurion s Radwahon Radiation purp e wiggles pan la iy mped Pressu e arrows Expansion allows quotupped radiu on Cycle begins again re qu yo escape 5m canls and pressure increases overcomes star s gravily decreases Gravin now compresses red arrows and makes i quotMmequot slur back lo original size and expand Cop ngh o Luminosiry solar uniis VCepheid and RR Lyrae Variables 104 quot 1037 39 The PeriodLuminosity 39 Relation 102 I I Ceph vo bles RR Lyrae mg 05 2 3 5 10 20 50100 Pulsa on period days B Why do we care about Cepheid Variable stars DISTANCE The periodluminosity relationship tells us the luminosity of a distant variable star if we measure the period If we know it s luminosity and apparent brightness we can calculate the distance to that star But this works for variable stars even in other galaxies millions of lightyears away THIS is how we ve come to know how big this universe really is At least one MORE way Tim 10 billion yrs spenl as i 5 New Age billions 9 yeah Io The Sun s Lifetime 7 10 billion years on the main Sequence 7 Once the hydrogen is consumed it Will enter the red giant phase 7 Helium burning begins starting the yellow giant phase Once helium is consumed core contracts reheats and the outer surface expands beginning the red supergiant phase Core begins to cool and the outer envelope expands again forming a plan etary nebula The core remains as a White dwarf The Lifepath of the Sun 39 H H mm years Fusing hem and vogen 2n ths H bilhon years Hehum 39m core igmles hehum Hash Fusmg hydrogen m mu around core E 3 g 2 E 3 II 11001 when years 39 IO mum yams Exposed cors d var 5w now45 waIcnyaurs cook and am Fusing hydrogen 5 core R imam fore purple as e gle uk strips off outer shell Carbon akes in red gianr s atmosphere gt Rudialion pushes c1 llo es Fla 392 stellar core p sh on gas As a red giant expands it cools 7 Outer layers cool enough for carbon akes to form 7 Flakes are pushed outward by the radiation pressure 7 Stellar gas is also draggedforced outwards 7 This drag creates a highspeed stellar Wind 7 Flakes and gas form a planetary nebula The Hourglass Nebula Nebula Shape End View llooks round Star Gas ejected from star 39 Side View l 0 lVhite Dwarf Stars At the center of the planetary nebula lies the core of the star a white dwarf This is the corpse Degenerate material Incredibly dense Initially the surface temperature is 25000 to 100000 K Quite hot Cools slowly until it fades from sight immuth n u r HA few AUH Companion star If a white dwarf is in orbit around a red giant companion star it can pull material off the companion and into an accretion disk around itself Material in the accretion disk eventually spirals inward to the surface of the white dwarf Novae Ifenough material accumulates on the white dwarfs surface lsion can be triggered anew at the surface causing a massive explosion This explosion is called a nova new as in new star Ifthis process happens repeatedly we have a recurrent nova P S hova expansion I d Supernovae If the mass of one of these accreting white dwarfs exceeds 14 solar masses the Chandrasekhar Limit gravity wins momentarily The additional gravity causes just enough compression This compression causes the temperature to soar and this allows carbon and oxygen to begin to fuse into silicon The energy released by this fusion blows the star apart in a Type Ia supernova Supernova This is a SINGLE STAR with a luminosity of BILLIONS of stars Luminosin solar units 100 200 Time days The light output from a Type la supernova follows a very predictable curve 7 Initial brightness increase followed by a slowly decaying tail All Type la supernova have similar peak luminosities and so can be used to measure the distance to the clusters or galaxies that contain them Radioactive Dating vunmdl39 rwmdu m m Km c mw Mr mnmc m pm a sum 5 n Hle m m a lawn w W I A number of naturally occurring I atoms undergo radioactive decay 7 The atom splits apart into lower n We can then use mdioactive dating to tell how old a roc is 7 The oldest rocks on Earth are around 4 billion years old mass atoms sslo 7 The time it takes for half ofthe 7 Even older samples have been atoms i a given sample to decay found on the n and in is called the material s halflife meteorites 7 After a number n ofhalflives All bodies in the solar system the fraction of original material Whose ages have so far been 16ft 5 determined are consistent with having formed about 45 billion years ago A Model of Solar System Formation 0 In Unit 32 it was pointed out that any model of the Solar System s formation must account for all observations 7 Planets revolve around the Sun more or less in the same plane 7 Planets rotate about their axes in the same direction as they revolve around the Sun 7 Rocky dense planets are found close to the Sun and gaseous bodies are farther from the Sun The most successful model ofSolar System formation is the Solar Nebula T hzmy 7 The Solar System originated from a rotating diskshaped cloud of gas and dust with the outer part ofthe disk becoming the planets and the inner part becoming the Sun Solar Nebula Theory 45 billion years ago the immense cloud of gas and dust that would become our Solar System began to contract due to gravity 7 As it contracted it attened into a disk and began to spin faster Conservation of Angular Momentum 7 Most of the material in the cloud moved to the center to become the Condensation and the Formation of the Planets As the material in the center gathered its temperature increased The rest of the disk began to cool and the gasses present began to condense 7 Near the center Where the temperature Was highest only silicates and metals could condense 7 Farther out Volatile gasses could condense The layout of our current solar system takes shape Planetesimal Formation In the inner solar system silicate rocky and metal grains accreted stuck together overtime to form rocky planetesimals These would become the terrestrial planets In the outer solar system icy These planetesimals collided and planetesimals formed gathered mass over millions of years to form the planets Protoplanets and differentiation Planetesimals grew through accretion y r I into protoplanets m aim my rm 7 W which were heated Cw by collisions and by W 7 radioactive decay and M Ma Ham mi m m W Denser material sank toward the center of the bodies and lighter material oated toward the surface This separation process is called differentiation inaimmnma we emiu39eri Atmospheres 0 THE atmospheres of the terrestrial planets formed last by either or both 7 Outgassing I Volatiles trapped inside the plan t escape Volcanoes or other Processes 7 Collisions I Volatiles could crust by collisions or Via direc delivery by comes Finding Young Planets in Their Formative Years We cannot watch a planetary system evolve it takes too long millions of years We can however find other stellar systems in various stages of development In the gas and dust of the Orion Nebula we find many protoplanetary disks disks of dark dusty material orbiting young stars The one shown here is only around 10 million years old a stellarsystem baby picture 0 We can View the disk Young Systems directly by blocking out the light from the young star at the center These images lend credibility to the solar nebula theory 56 billion miles Q Diameter of Neptune s orbit Detecting Exoplanets We can detect planets around other stars by using the Doppler Shift method 7 A planet and its star revolve around a common center of mass 7 We cannot detect the planet directly but we can detect the resulting wobble in the star 7 As the star approaches us in its orbit its spectrum will be blueshifted As it recedes the 7 spectrum will be red Star receding lines redshi ed LI Shifted Detecting Exoplanets continued Astronomers can also use the transit method 7 We look for dimming of light from the central star as the planet eclipses the star passes between us and the star Both the transit method and the Doppler Shift method requires the distant planetary system to lie in a plane that is parallel to our point of View If the distant planet is large enough or our telescopes powerful enough we can detect distant plants by directly Viewing them Jupiter Sized Worlds Most planets we have detected are very large Several Jupitermasses The planets we detect must be 0 O 0 large in order to create a large Earth Jup39iter A a c enough Doppler wobble 0003 I 072 2 A 7 Some objects detected are not planets but brown dwarfs Stars too low in mass to fuse hydrogen This does not mean there are no smaller planets out there we just can t see them yet Approximate relaiive size of planeis Upsilon Andromedue sysiem The First Picture of an Exoplanet A distant planet orbitting a brown dwarf star Young star millions not billions years old with planet Infrared image No Data Goran agrap h Mask 5 E3123 Sca ered fquot r v i 43 Light madam Nmseu Fir quot Cquot 415 s EIti 513 No Data 533 gig Isaac Newton 16421727 l l Isaac Newton discovered the fundamental laws that govern the motion of all large bodies Had to invent his own mathematics Calculus to do it His work is used even today in calculating everything from how fast a car stops when you apply the brakes to how much rocket fuel to use to get to Saturn And he did most of it before his 24Lh birthday rTNFj c mm llmMcherilICmu mme Ptmmsmnre Warm roduumnordinlo In 5 v x p l y Spcods up Slows down gt gt 2 gt 5 sad remains conslo m 90000 P Mass and Inertia Mass is the amount of matter an object contains Mass is different from weight weight requires gravity or some other force to eXist Example while swimming you may feel somewhat weightless because your body oats Your mass however stays the same Inertia is the tendency of mass to stay in motion or at rest The Law of Inertia Newton s First Law is sometimes called the Law of Inertia 7 A body continues in a state of rest or in uniform motion in a straight line at a constant speed unless that state is changed by forces acting on it 7 Or a body maintains the same Velocity unless some force changes it 7 It does NOT take force to make a moving object move it only takes force to CHANGE its motion A ball rolling along a at ictionless surface Will keep going in the same direction at the same speed unless something pushes or pulls on it gt Another View of Newton s First Law If an object s velocity is changing there must be forces present 7 Dropping a ball 7 Applying the brakes in a car If an object s velocity is not changing either there are no forces acting on it or the forces are balanced and cancel each other out 7 Holding a ball 7 Driving down the road a constant speed in straight ine npyxglu o the Mcomwm Compamei l c Balanced Forces no change in velocity What s a Vector Victor A vector is a physical quantity that requires both a magnitude or size and a direction to fully de ne it Force velocity momentum angular momentum and acceleration are all examples of vector quantities A scalar is a physical quantity that can be fully de ned by magnitude or size only Length area volume temperature energy are all examples of scalar quantities Acceleration Cnpynglu lthLGlawrllill Companies Inc Permission required 01 upmducnom urdixplny Acoelemn w warm Marian Same Speed m sum dimchun change A mead Acceleration A mug in dream A I C The term acceleration is used to BUT a change in an object s describe the change in a body s direction is also acceleration velocity 7 Turning the steering Wheel of a car Stepping on the gas pedal of a car makes the car go left or right 7 this accelerates the car 7 it increases is an acceleration the speed 7 Forces must be present if there is 7 Stepping on the brake accelerates any acceleration decelerates the car 7 it decreases Circular Motion Side View Top View A string tied to a ball and swung Where s the force around your head It s the tension in the string that is Law of Inertia says that the ball Changing the b31175 VelOCitY should go in a straight line If the string breaks the ball will Ball goes in a circle there must mOVe Offin a Straight line While be forces falling to the ground Centripetal Force This force that causes circular motion is sometimes referred to as the centripetal force a force directed towards the center of the system Cnpynghl z m M xawrhll Compmm Inc vmumnn inquired rm mpmdumou nrdliplav The tension in the string provides this force Newton determined that this force can be described by the following equation mgtltV2 N ewton s Second Law CupynghKDYI mammal Companies Inc I zumwm lzqmred formprndualcn mum o The net force F acting on an Sm Empmmge object equals the product of its F cce39e quot 39 39 acceleration a and its mass m i 0 Fmgtlta Full corl small occelero on a 0 We can rearrange this to a Fm For an object With a large mass the acceleration Will be small for a given force Though simple this expression 0 If the mass is small the same can be 986d to calculate force will result in a larger everything from how hard to hit acceleration the brakes to how much fuel is needed to go to the Moon When two bodies interact the forces between them are always equal and oppositely directed If two skateboarders have the same mass and one pushes on the other they both move away from each other at the same speed but in opposite directions If one skateboarder has more mass than the other the same push will send the smaller person off at a higher speed and the larger one off in the opposite direction at a smaller speed Newton s Third Law Copynglu mm Mccmwnm Companies ne Pe mmDn This works for everything planets too l y A 39 u v 7 a V 2 We know that for planets the centripetal force that keeps the planets moving on an elliptical path is the gravitational force We can set FG and FC equal to each other and solve for M a xV2 G This M is the mass of the center object the larger object o If we know the orbital speed of an object orbiting a much larger one and we know the distance between the two objects we can calculate the larger object s mass M Masses from Orbital Speeds l Bl mlsHul required For reprwluulmn or dnylnv Magv10 d2 Copyright a he mam r l anie v39EE39bT FGG Newton applied his ideas to N iyton s Modification of Kepler s 3rd Law opvligh a live Me mwrlhil for reproduction or mm Kepler s 3rd Law and developed a version that works for any two massive bodies 3 MA MB A YR Here M A and M B are the two object s masses expressed in units of the Sun s mass This expression is useful for I calculating the mass of binary star systems and other astronomical phenomena N I I I I Blackbodies I I A body that absorbs all energy incident on it and emits energy of all wavelengths is called a blackbody The Sun a stovetop element or a piece of charcoal approximate a blackbody The Blackbody Spectrum t ilt As a blackbody is heated the l IIADDK Y 5800K 7 MM atoms 1n 1t start to move faster am 250 hm am 500 um Am IOOO Am and faster 2 7 When they collide they ernit a photon with an energy 39 proportional to how hard they hit Some collide lightly and produce longwavelength i i n rad a1 0 Some collide very hard and radiation Most are somewhere in Gentle collisions between 7 As the body gets hotter the number of collisions 39 00 39500 increase and the number of WM WH quotW 39 hard collisions increase anqhmon gt Hard collisions tigi rbul n marten 39r t arar Euls Mud viiiteen L Measuring Temperature it 1lt It is useful to think oftemperature in a slightly different Way than We are accustomed to 7 Temperature is ameasure ofthe motion ofatoms in an object a Objects with low temperatures have atoms that are not moving uch e Objects with high temperatures moving around Very rapidly The Kelvin temperature scale Was designed to re ect this 7 0 K is absolute zero rthe atoms in an object are not moving at all Additional collisions mean that more photons are emitted so the object gets brighter Additional hard collisions means that more photons of higher energy are emitted so the object appears to shift in color from red to orange to yellow and so on Of course we have a Law to describe this 4 Resplts of More Collisions lg ma holler burner glows more mango man he cooler bumer 23 S 396 Wien s Law and the tefanBotzmann Law m am he mm M A Wien s Law 0 SB Law 7 Hotter bodies emit more 7 The luminosity of a hot body strongly at shorter rises rapidly wi wavelengths The hotter it is temperature the shorter the wavelengths Taiking 5the Temp39erature 0R Astronomical Objects I l l r if 0 Wien s Law lets us estimate the temperatures of stars easily and fairly accurately 0 We just need to measure the wavelength kmax at which the star emits the most photons 0 Then 0 If we know an object s temperature T we can calculate how much energy the object is emitting using the SB law 4 L 2 0T 0 cs is the StefanBoltzmann constant and is equal to 567gtlt10398 WattsmZK4 The Sun pus out 64 million watts per square meter 7 lom of energy The tefanBoltzmann Law Triangulation wwunvnmmmmwa mm m Wm mm mm a my Scale drawing of measured triangle A B We can use triangulation to calculate how far away objects are cm by Triangulation ropy gm mm Mm imelH Compama m The Moon is a relatively close Amusuonrequiredforrcpmducum ordiwlny object and measuring the V y 39 Ob necessary angles 1s not too dis f39 2pm dlfflcult minsgrgungles d Distance Other astronomical objects of interest are much farther away and measuring the necessary angles in degrees is impractical Degrees have been subdivided f into arcminutes and arcseconds a 7 1 degree 60 arcminutes Kb 1 7 l arcminute 60 arc seconds From baseline b and angles A and B1 solve for d by trigonometry Apollo astronauts left nce to the Moon faceted mirrors behind when returned to Transmitted signal quot leaves Earth traveling at speed of light c Scientists can bounce 2d ct laser beams off these mirrors and measure the time it takes the laser pulse to travel to d Distance to Moon Reflected signal traveling at speed the M0011 and back of light c arrives back at Earth 1 We know the speed of seconds wen light c so calculating the distance is eaSyl Radar or laser beam transmitter As a person s Viewing Parallax Cprriglko 1h VIL39KimwAHill Companies I inn required for rzpmducuuu urdiipIy location changes foreground objects seem to shift relative to background objects This effect is called A parallax and can be used to measure the distance to closer astronomical objects Viewed Irom right Viewed hem Isl e Using Parallax 5m ka l kn n g s here In My m We w H mm M January I mug cl m A V 39 Eu h m M Trigonometry gt 1 AU Circumference Cummrmncs 21x 1 pa 2m A 7 1 avcsec 7 I 211 1295000 arm 1293000 Crexs mulhp y lo gs 0 AU d 2 206265 AU 2 BOVXIDHkm Moving Stars The positions of stars are not fixed relative to Earth 7 They move around the center of the galaxy just as Earth does 7 This motion of stars through the sky independent of the Earth s rotation or orbit is called proper motion 7 Over time the constellations will change shape Here delta 50000 yr The speed of a star s motion toward or away from the Sun is called its radial velocity Doppler shift l i A problem Parallax method has its limitations Earth s atmosphere interferes with angle measurements for stars beyond 100 parsecs away Spacebased scopes Hipparcos gets us out to 500 parsecs But just in our galaxy stars are 1000 s tens of thousands 100 s of thousands of parsecs away Now what Light and Distance Brighter objects are not necessarily the closer objects Comet Halley to the upper left is within our Solar System The background stars are just as bright but tens hundreds or thousands of light years more distant The total amount of energy a star emits to space is its luminosity measured in watts The amount of light reaching us from a star is its brightness Cowism o n a 7 as phoionsmz 3 z 2 Dixlancs A39s l quot A star emits light in all directions like a light bulb We see the photons that are heading in our direction As you move away from the star fewer and fewer photons are heading directly for us so the star seems to dim 7 its brightness decreases if 7 A phclcnxmz 4m2 9m1 eGmwA lll Compamu Inc Pumisumuqmred for reproduction Mammy 7 A photonsm1 35 phomns The brightness decreases with the square of the distance from the star 7 If you move twice as far from the star the brightness goes down by a factor of 22 or 4 Luminosity stays the same 7 the total number of photons leaVing a sphere surrounding the star is constant m m MK er l chmnn tequirzd I39m Icpmdum rmumnm Inn on or diwlny Youlgsee this every day More distant streetlights appear dimmer than ones closer to us It works the same with stars If we know the total energy output of a star luminosity and we can count the number of photons we receive from that star brightness we can calculate its distance d L 473 Some types of stars have a known luminosity and we can use this standard candle to calculate the distance to the neighborhoods these stars live in We can quantify the brightness of a star by assigning it an apparent magnitude 7 Brighter stars have lower magnitudes possibly negative numbers 7 Dimmer stars have higher positive numbers Differences in magnitudes correspond to ratios in brightness 7 Ex One star of interest has a magnitude of 6 dim and another star has a magnitude of l easily seen The magnitude difference of 5 means that the brighter star is 100 times brighter than the dimmer star stars luminosities if they were at the same distance from the Sun We can calculate how bright the stars would appear if they were all the same distance from us say 10 parsecs The magnitude of a star moved to 10 parsecs from us is its absolute magnitude Copyrighl l h MEanrlIill Company In Permiuion mun far upmducncm nrdiiplay Spoclmm of light leaving my Earth 1 Dark nbsnrprmn 4m New in mm ulmnsphure absorb lighl at particular wavelengths Less ligh of Ihese wavelenglh leaves my Eleaan energylmr Ivansm39ans Viola lighl i ubxorbld as it was amongstquot luvl 2 m 5 n Ii 5 eladlons rm level 2 70 4 m oval 2 1 3i Ulrmvlelet wavelengrhs are absorbed as um Im elecnnm up i lmm level I lnlruted wavelengths are absorbed as they rm elemquot up rmquot Iml a Hydvogencram Photons have a dif cult time moving through a star s atmosphere Ifthe photon has the light energy it will be absorbed by an atom and raise an electron to a higher energy level Creates absorption spectra a unique ngerprin for the star s composition The strength of this spectra is determined by the star s temperature ropmgm 9 lb mam Pemuuion teamed farm I 39nmpames he I amalgam Rigel O Hn pmduunm nrdlxplay face Temperatures Remember from Unit 23 that the peak wavelength emitted by stars shifts with the star s surface temperatures 7 Hotter stars look blue 7 Cooler stars look red We can use the star s color to estimate its surface temperature 7 Ifa star emits most strongly in a wavelength 7L in mm then its surface temperature T is 729x106Knm z T This is Wien s Law re with Wein s Law Cupylighx 39l h mammal Campamay Inc Pumiwmuqmrzd for reproduction mduplay 400 m 700 nm 12000 K w m u PM L w A00 600 00 wmxengm Hm 29x106Knm A T Around 1901 nnie Jump Cannon developed the spectral classi cation system Arranges star classi cations by temperature Hotter stars are O type Cooler stars are M type New Types L and T Cooler than M ctral Classification CopyngthIhe comm Companies Inc Varnuwom required forrepmduavun mdiiplay e iUm H39 Absorpiion Hydrogen sirengih r gt 0 E 39 B A F G K I M T Q u x w i Titanium oxide 0 From hottest to coldest they are OB AFGKM Mnemonics Oh Be A Fine GirlGuy Kiss Me Or Only Bad Astronomers Forget Generally Known Mnemonics Calcium r The Nature of Light Mngnphr quotmy Asawave A small disturbance in an electric eld creates mall magnetic eld Which in turn creates a small electric field and so on a self propagating electromagnetic wave Light Waves can constructively or destructively interfere The color of light is determined by its requeney Light is radiant energy Travels very fast 7 300000 kmsec 186000 milessec Has a dual nature Can be described either as a wave or as a particle traveling through space As a particle 7 Particles of light photons tmvel through space 7 These photons have very speci c energies that is light is quantizedquot 7 Photons strike your eye or other sensors like very small balls and are detected Light from a distant source seems very dim Why Is it because the photons are losing energy No 7 the light is simply spreading out as it travels from its source to its destination The farther from the source you are the dimmer the light seems The object s brightness or the amount of light received from a source decreases with increased distance The relationship is mathematical Brightness T otal Light Output 4m2 This is an inversesquare law 7 the brightness decreases as the square of the distance d from the source Magnetic energy An atom has a nucleus its center containing protons and neutrons Outside of the nucleus electrons move in clouds called orbitals 7 Electrons can also be described using wave or particle models 7 Electron orbitals are quantized 7 that is they exist only at very specific To move an electron from one orbital to the next higher one a specific amount of energy must be added Likewise a specific amount energies of energy must be released for an electron to The lowest energy orbital move to a lower orb1tal is called the ground state These are called electronic transitions Ihe Chemical Elements The number of protons atomic number in a nucleus determines what element a substance is An atom that is neutrally charged has a number of electrons equal to the number of protons The electron orbitals are different for each element and the energy differences between the orbitals are unique as well This means that if we can detect the energy emitted or absorbed by an atom during an electronic transition we can tell what element the atom belongs to even from millions of light years away Absorption If a photon of exactly the right energy equal to the energy difference between orbitals strikes an electron that electron will absorb the photon and move into the higher orbital 7 The atom is now in an excited state If the photon energy doesn t match any of the orbitalenergy differences it can not be absorbed 7 it will pass through We say the element is transparent to those frequencies or colors a ray with m were Abscvpllnn of Ilghl by a hydrogen mm This process is called absorption If the electron gains enough energy to leave the atom entirely we say the atom is now ionized or is an ion Emission If an atom drops from one orbital to a lower one it must first emit a photon with the same amount of energy as the orbitalenergy difference This is called emission Difference in energy becomes light a pholun 4i Prolole b a I E w in 4 Emission of light by a hydrogen alum 7 7 Increasing energy 77 77 WWWM Light Increasing wavelenglh y In Astronomy it is far too difficult to Visit stars and most planets in person Astronomers primary tool in learning about the universe is electromagnetic radiation or light 0 The colors that the human eye can see define the visible spectrum but there is much more to light than this narrow band of color Wavelength A cw Wavelengths ofvisible light are very small 7 Red light has a wavelength of 7x107 meters or 700 nanometers nm 7 Violet light has a wavelength of 4x107 meters or 400 nm 7 Colors in between red and violet remember ROY G BIV have intermediate wavelengths The colors we see are determined by the wavelength of light Wavelength is the distance between successive crests or troughs in an electrom agnetic wave This is very similar to the distance between the crests in ocean waves We denote the wavelength of light by the symbol 7L Increasing energy A g j 1 L 1 V A l V 4 Increasing wavelength Sometimes it is more convenient to talk about light in terms of frequency or how fast successive crests pass by a given point You can think of frequency as a measure of how fast you bob up and down as the waves pass by Frequency has units of Hz hertz and is denoted by the symbol v Long wavelength light has a low frequency and short wavelength light has a high frequency Copy ghxe r chwNill ompumeg ne Pamlnianmuvmdformpmduumnmduplay Frequency and wavelength are related by xvzc Where 0 is the speed of light Increasing energy mil Uni in If i F X quot l l y I lli u v J J Increasing wavelenglh Light from the Sun arrives with all wavelengths and we perceive this mixture of colors as white White iighi sunlight Newton demonstrated that white light could be split into its component colors with a prism and then recombined into white light with a lens A White light Lw The Eleetro39m agnetic Spectrum I There is more to light than just meSunana Col mers39ellar Acme d s ohersars lou alox Y v1s1ble light Radio waves have very I l l long wavelengths as much 4 Increasing energy as a meter and more WWWW Microwaves like the ones lncreoslng wavelength 00001 nm em nm Ion 1000quot wow lOmm lm lOOm we cook are at the Rquot upper end of the radio part RodarW FM AM of the spectrum Infrared wavelengths are longer in wavelength than visible light mm The Electromagnetic Spectrum Increasan energy WWW mm mm m at 0 Above the visible C A cloud galaxy Ultraviolet waves are shorter in wavelength than visible waves These included the waves that tan or burn us Xrays come mostly from WW stellar sources and can M W penetrate many materials like skin muscle and bone Gamma rays have the shortest wavelengths i l I 7 Energy Carried by Photons magma 39 A photon carries energy with it olher stars cloud galaxy C that is related to its wavelength or frequency h x c l E h x V Increasing energy WWW increasing wavelenglh From this we see that long quot quotm 39 quot 39 quot m m m wavelength low frequency photons carry less energy than short wavelength high frequency ones This is why UV waves give us a sunburn and Xrays let us look through skin and muscles Rn in wnvFK Radar TV FM AM if j W Steeing Spectra xx 1 C i 3 l c l 0 Seeing the Sun s spectrum is not dif cult A narrow slit only lets a little light pass Either a grating or a prism splits the light into its component colors If we look closely at the spectrum we can see dark lines These correspond to wavelengths of light that were absorbed Imagine that we have hot i H 3 hydrogen gas Collisions among the hydrogen atoms cause electrons to jump up to higher orbitals or energy levels Electrons can jump back to lower levels and emit a photon of energy h If the electron falls from orbital 3 to orbital 2 the emitted photon will have a wavelength of 656 nm If the electron falls from orbital 4 to orbital 2 the emitted photon will have a wavelength of 486 nm g DE 1 Emission Spectra m hydrogen atoms For clavlty only rm lnnnr four elemquot crblls are shown quotan quot4 quot Red ham Eur A 1555 um n 3 Blue lghr Mair ln m In this hydrogen mom on gleam is a mprng m av mm mm It 2 The mm ham 0 We can monitor the light emitted and measure the amount of light of each wavelength we see If we graph this data we ll see an emission spectrum Edyman m of orb mli Ma Q n e 39 as rm of hydrogen This spectrum is unique to hydrogen If we were looking at a hot cloud of interstellar gas in space and saw these lines we would know the cloud contained hydrogen Rf C m t Different atodelf erent spectrum Every element has 1 its own spectrum trmlw Note the differences between hydrogen and helium spectra below IIII Helmm Hyimgen quotK ii 7 7 Absorption Spectra What if we had a cloud of cool hydrogen gas between us and a star 7 Photons of energiees that corresponds to the electronic transitions in hydrogen will be absorbed by electrons in the gas 7 The light from those photons is effectively removed from the spectrum 7 The spectrum will have dark lines where the missing light would be 7 This is an absorption spectrum 7 Also unique for each element VVIIVIJIII Mogne a fS ectra Summary 39 wi l A V apyngmc lhe Mc mwr lll om rum r mmuformpmducnm 3125 If the source emits light that is Con39inUOUS SPECWT continuous and all colors are present we say that this is a continuous spectrum A If the molecules in the gas are well separated and moving rapidly have a high temperature the atoms will emit characteristic frequencies of light This is an emissionline 3 Spectrum Emission line spectrum hydrogen gas If the molecules of gas are well separated but cool they will absorb light of a characteristic frequency as it passes through This is an C absorption line spectrum Absorption line spectrum hydrogen gas 5mm of a cam 5am specrmm A Enghiness Come 400 Wovelsngrh Hvdl oge lc m x C k J Magnum Bughlness 500 Wovelenglhl m B Sodium gt00 Sun You have experienced the Doppler shift in sound 7 Standing on the sidewalk watching cars go past 7 As a car approaches the sound from the car seems to have a higher pitch 7 this is due to shorter wavelengths 7 As the car passes the sound shifts to lower pitch due to the longer wavelengths 7 Police radar guns work on the same principle The waves re ected off the car will be shifted by an amount that corresponds to the car s speed 39 quotD o pplerShift in Light If an object emitting light is moving toward you the light you see will be shifted to shorter v wavelengths toward the blue end of the spectrum We say the light is blueshifted Likewise if the object is moving Blueshi away from you the light will be redshifted 0 If we detect a wavelength shift of A away from the expected Wavelengm wavelength 7 the radial line0f decreased sight velocity of the object is Bulb moves From 1 to A VR x c l Redshift Wavelength increased


Buy Material

Are you sure you want to buy this material for

25 Karma

Buy Material

BOOM! Enjoy Your Free Notes!

We've added these Notes to your profile, click here to view them now.


You're already Subscribed!

Looks like you've already subscribed to StudySoup, you won't need to purchase another subscription to get this material. To access this material simply click 'View Full Document'

Why people love StudySoup

Jim McGreen Ohio University

"Knowing I can count on the Elite Notetaker in my class allows me to focus on what the professor is saying instead of just scribbling notes the whole time and falling behind."

Anthony Lee UC Santa Barbara

"I bought an awesome study guide, which helped me get an A in my Math 34B class this quarter!"

Steve Martinelli UC Los Angeles

"There's no way I would have passed my Organic Chemistry class this semester without the notes and study guides I got from StudySoup."

Parker Thompson 500 Startups

"It's a great way for students to improve their educational experience and it seemed like a product that everybody wants, so all the people participating are winning."

Become an Elite Notetaker and start selling your notes online!

Refund Policy


All subscriptions to StudySoup are paid in full at the time of subscribing. To change your credit card information or to cancel your subscription, go to "Edit Settings". All credit card information will be available there. If you should decide to cancel your subscription, it will continue to be valid until the next payment period, as all payments for the current period were made in advance. For special circumstances, please email


StudySoup has more than 1 million course-specific study resources to help students study smarter. If you’re having trouble finding what you’re looking for, our customer support team can help you find what you need! Feel free to contact them here:

Recurring Subscriptions: If you have canceled your recurring subscription on the day of renewal and have not downloaded any documents, you may request a refund by submitting an email to

Satisfaction Guarantee: If you’re not satisfied with your subscription, you can contact us for further help. Contact must be made within 3 business days of your subscription purchase and your refund request will be subject for review.

Please Note: Refunds can never be provided more than 30 days after the initial purchase date regardless of your activity on the site.