Exam Three Review (The Final)
Exam Three Review (The Final) Astr 1010-100
Popular in Introductory Astronomy 1
Popular in Astronomy
This 6 page Study Guide was uploaded by Alyssa Karounos on Friday March 13, 2015. The Study Guide belongs to Astr 1010-100 at University of Washington taught by Dr. Oliver Fraser in Winter2015. Since its upload, it has received 168 views. For similar materials see Introductory Astronomy 1 in Astronomy at University of Washington.
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Date Created: 03/13/15
Exam Three Review 0 Describe various methods for measuring cosmic distances standard candles cepheids main sequence tting Hubble s law 0 Cepheid Stars in a magellanic cloud varies in brightness as it ickers The longer the period the farther the star 0 Looking at spectra of galaXies they are all redshifted moving away from us The faster they appear to be moving the farther away they are Hubble s Law 0 Standard candles is when you light a standard candle and compared its brightness to that of what you re measuring 0 Relate measurements of galaxy recessional velocities to their distance 0 v H 061 O The farther away the faster it will be receding O Relate the hubble plot to the age of the universe 0 The eXpansion of the universe doesn39t look like an eXplosion There must have been a point in time where things were formed to push them out this way If the universe is infinite but not in nite in age then it is possible it is both homogenous and isotropic mm r a vaults 7 7 V 7 1 nu music s FIGURE ll 39 Q VelocitysDistmue Relation among ExtraaGallactic Nebulae o Interpret Schwarzschild radii and event horizons for black holes of different masses 0 Things that have gravity has escape velocities where you must be going a certain amount of speed to eXit the gravitational force Black holes have so much gravity that the escape velocity is greater than or equal to the speed of light meaning light can t get through light can only travel through this imaginary surface in our direction Any signal travels at v S c so information can only ow in one direction in This radius is after called the event horizon 0 Explain how black holes are observed 0 From outside the event horizon it s just another massive object gravity works the same as always Mass gravity bends the spacetime around the black hole distorting what we can see Because a black hole has too much mass we see the back of it as the light is bent 0 List the effects of special relativity O The speed of light is a xed number c Instead of measuring speeds relative to motion relativity predicts that time is relative to motion Mass increases as you go faster Light can never move slower o Predict how light moves near massive objects 0 Light will keep moving in a straight line but because we are sitting in a gravitational eld and accelerating the beam drops Einstein predicts that the light from stars should bend as it grazes sun s surface moves away from us The mass bends the light 0 Explain the evidence for dark matter 0 The normal matter that we don t see directly but the effect of this gravity Galaxies exist within huge clouds of dust Measure dark matter by comparing visible mass to actual mass Visible mass is due to stars gas and dust Actual mass is measured using either motions or directly form curved spacetime The visible makes the invisible visible We know that there is invisible mass bending light therefore dark matter 0 Identify the structures that compose the Milky Way 0 Disk I the disk is very thin so that we can see out of it I there are arms 0 Buldge I center of gravity I orbits are not uniform I there is a black hole in the center 0 Halo I spherical shape surrounded the galaxy which houses globular clusters 0 Link present day evidence to the formation story of the Milky Way 0 We know that stars that have heavy metals must be newer generational stars By looking at the stars that have strange orbits we conclude that they must be in the halo The Stars in the halo are older first generation starts compared to the stars in the disk that are newer generation stars At first the Milky Way was a huge ball of gas that started to compress itself and spin The globular clusters continued their intended orbit as the gas now in the shape of a disk has started to form new stars Eventually this separated the disk and the halo 0 Describe evidence for the Big Bang model beyond expansion of the universe 0 The Cephiod periodluminosity relationship tells distance Almost all the galaxies are redshifted moving away from us These lead directly to the two axes of the hubble plot The Beginning was so hot it ionized everything opaque The recombination to form the electrons and neutrons into atoms There was expansion cooling Electrons lose energy and aren t bouncing all the time The recombination of the electrons and neutrons into atoms The universe is transparent Creates photons and is glowing All the giving of light starts traveling The photons should still be around and hitting the universe If you stretch something uniformly the objects on top will move away from the center and each other Father ones seem to be moving away faster Compare and contrast disk and elliptical galaxies 0 Disk I a bunch of stars orbits in the same direction around a middle bulge I the arms are made of new stars and is very thin I the orbits in the bulge are not uniform I more blue because there are still producing new stars 0 Elliptical football 3D shaped orbits at all random directions all the mass is focused in the center redder because the light is mostly from red giants not producing new stars Identify the orbits that create structures in galaxies O The disk galaxies will have uniform orbits in the disk section and very random orbits in the bulged O elliptical galaxies will have very different orbits Explain how we know a supermassive black hole exists in the center of our galaxy 0 Center of our galaxy is a constellation sagittarius We see an expanding shell After observing what orbits the center we used Kepler s law to gure out the mass of the central object With a period of 13 years and a semimajor axis of 800 Au the mass equals over a million solar masses This has to be a black hole Nothing else is as massive and as small Describe the current model of galaxy formation and evolution 0 Time was dark matter and normal matter and radiation It was small and hot and dense If pressure of light smooths out radiation and normally matter Dark matter doesn39t care about light and stars clumping Now we have Clumpy Dark Matter with smooth normal matter and radiation These clumps of Dark Matter help form dwarf galaxies Minor mergers are the most common mergers where a dwarf galaxy merges into a Maj or galaxy We think dwarf galaxies merging together have created major galaxies A major merger is two major galaxies merging together What tends to happen is that the dust and the stars all accumulate into one bulge similar to an elliptical galaxy Predict the future size and expansion rate of the universe from measurement in the past 0 By looking at Supemovae very far away from us we can see supernovae farther in the past From looking at the Hubble plot adding this new data it seems that the universe is expanding faster than it was in the past 0 List the characteristics of the habitable zone around stars 0 the region around a star within which planetarymass objects with sufficient atmospheric pressure can support liquid water at their surfaces This zone will move farther away from the star over time varying in lengths OB A stars have a very short habitable zone life F and G stars have a perfect time span and K and M stars have a long life that is still uninhabitable due to closeness 0 Describe the meaning of the individual stellar classifications 0 What causes these lines is that atoms have particular energy spectrums for their electrons By looking at spectrum lines we deduced that the sun and the universe are made of the same things we are Williamina Fleming devised a system of classification of stars based on the strength of the hydrogen lines on a spectra From AO A having the strongest and 0 having the least OBAFGKM letters were chosen because they are most easily distinguished based on hydrogen lines out of all Annie Jane Camp redevised a system of classification based on temperature using Fleming s hydrogen line classifications This gave us 0 stars as the hottest down to M being the coolest OBAFGKM 0 Describe the meaning of the order of star classification OBAFGKM O The individual letters tells you temperature of star and strength of hydrogen lines on the spectra The order is from hottest to coolest 0 Evolution of a star SPECTRAL CLASSES O B A F G K M I I I I I I I 10000 RED GIIANT 1000 39 GASEOUS 100 CLOUD dard of comparison PROTOSTAR LUIVIINOSITY The sun1 being taken as the stan 110 W100 WHITE DWARF I l l I 40000quot 30000D 20000quot 15000 100000 5000 4000 3000quot SURFACE TEMPERATURE In degrees Kelvin O O HR diagram O i m lien1 9 h aEIJug 515mb mam 111 1 a EilJ Eil39gi t 111 I Eire r n1 K a 1 V 21 55 n 7 Vi 1393le i R wrl39s i mguu no a manmn a IT 139 a 39 A E j m gag 3 Z I t 599quot r x E 2 E I g E 2 39EL l 2 33 13911quot ij a z 39 j39 39z g l 1393393 Iiiil a against Dwar w E l i l i E Tempemtu rt If 0 Moon Phases The moon s E wdlllESE dance AS the Earth and moor orbit the sun thEEI IEn Final and night on the lunar v t We refer to the H on the ui ibllE szIEE 1315 me moon 35 thg rr39ujgn39E quot39plharge Tinare are major named IDHEIEEE that have been knotinn p throughout human history GENE comma EM 12151 I45 FREE imam HIDDEN mireu SMITH LASr METER WhHIINIE CRESCENT ff F WMHING 15 5E EH El EBDUS quot rams E HTHl Whit HIE EIIEIaE LHS WAIZEMG EEEEEEMT 151 QUhRTIEFE EE39LIHLT H3513quot o Lunar Eclipse O 0000 SunEarthMoon Moon goes away for a few hours Moon is at full If there is a shadow of light on the moon it is a lunar eclipse only people on a night time side Will experience this O EFT mm 0 Solar Eclipse 0 00000 Sun Moon Earth Sun goes away for a few minutes Moon does not fit in front of the sun perfectly because it is on a tilt A ring of light around a black circular object is a solar eclipse The moon will be a New moon phase only people in a small area will eXperience this Mme Prunu h rn i 39 in rmH i
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