Segment 5 Review Slides PDF

Nordgren Photography Tyler Nordgren (University of Redlands) Photography Site (Acadia, Big Bend ) Talk at UNL on Youtube in 2009  Class 5.1 11/20/2024 Announcements Exam 4 – range of results 67.8 ± 19.6 still quite a few (14) still need to take it Segments 5 moves a...

Nordgren Photography Tyler Nordgren (University of Redlands) Photography Site (Acadia, Big Bend ) Talk at UNL on Youtube in 2009  Class 5.1 11/20/2024 Announcements Exam 4 – range of results 67.8 ± 19.6 still quite a few (14) still need to take it Segments 5 moves a little more quickly There used to be 6 segments, so solar system the last week Tonight’s forecast: Clear! Citizen Science Topics – Several Fit well Tyler Nordgren Photography PI Questions Exercise 5.1a: Milky Way Galaxy Shapley & Hubble Exercise 5.1b Variable Stars as Standard Candles (if time) Milky Way 10,000 ly Scale What Letter Bright best represents Stars the location of each bright star? Star Distance Letter Sirius 9 ly A Vega 26 ly A Spica 260 ly A Rigel 810 ly A Deneb 1,400 ly A Milky Way 10,000 ly Scale Bright Clusters What Letter best represents the location of each bright cluster? Star Distance Letter M34 (Pleaides) 380 ly A M1 (Crab) 630 ly A M71 (Globular) 12,700 ly C Milky Way 1 cm=10,000 ly Scale What Letter best represents the location of To Sagitarrius each nearby Dwarf Galaxy galaxy? Star Distance Letter Saggitarius Dwarf 80,000 Elliptical Galaxy Large Magellanic 160,000 Cloud (LMC) Andromeda 2,600,000 Galaxy (M31)  Conclusions When we look out into the night sky We are seeing things that are pretty close by in the Milky Way Bright stars are really close by Clusters are at least on “our side” of the Milky Way There are only 3 objects we can see with our naked eye that our outside of the Milky Way LMC SMC Andromeda Galaxy All very close to us in the universe Clusters Globular Cluster Open Cluster  Astronomical Historical Overview ~1600 (Copernicus/Brahe/Kepler/Galileo/Newton) – nature of the SS 1700s – A lot of work on stars ~1800 (Herschel) Counting Stars – A “grinding stone” model of the Milky Way 1900s – Shapley – Hubble  Harlow Shapley (1885 – 1972) observed globular clusters determine their distance with RR Lyrae stars mapped their locations assumed center of the distribution of globulars was the center of milky http://www.wsanford.com/~wsanford/exo/rosse/rosse_m99_75dpi.jpg Found distance to center Shapley mistakenly thought "spiral nebulae" were in our own galaxy Spiral Nebulae Drawing  The Great Debate Shapley Curtis The Shapley-Curtis Debate in 1920 before the National Academy of Sciences. Both gave talks entitled “The Scale of the Universe. Shapley (Mount Wilson Observatory) argued that “spiral nebulae” were just nearby gas clouds and that the Universe was composed of only one big galaxy. He had the scale of the Milky Way and our location in it largely correct. Curtis (Allegheny Observatory) argued that the universe was composed of many galaxies like our own. He had the sun at the center of a small Milky Way. Shapley-Curtis Debate Site Edwin Hubble (1889-1953) Observed and categorized many other galaxies used a Cepheid to find the distance to the Andromeda Galaxy -- far greater than distance to center, showed "spiral nebulae" were "Island Universes" Hubble's Law Stellar Profile: Polaris very near NCP, (he North Star) Triple system (w/other stars nearby) w/mass determined from orbit Yellow Supergiant Luminosity = 1,260 L Surface Temperature = 6,000 K F7 1b star Radius = 38 R Mass = 5.4 M Age = 70 Myr Cepheid Variable (low amplitude, P~4 days) Distance = 430 ly (the closest type I Cepheid) Important for “calibration”  Class 5.2 11/22/2024 Announcements NAAP 5 was distributed Peer Instruction on Metallicity Metallicity Discussion Question Exercise 5.1a Milky Way Galaxy (breakout groups) Summarizes 5.1 and 5.2 Peer Instruction on Rotation Curves Black Hole at Center Dark Matter Vera Rubin Discussion Question Metallicity is an important parameter for describing a star. How does a star get its metals? (Where do they come from?) What does a star’s metallicity tell you about it? What is metallicity a proxy for? Standard Candles  Exercise 5.1b: Variable Stars as Standard Candles RR Lyrae Stars – All RR Lyraes have absolute magnitudes of about M = 0.5 – Thus one observes m, assumes M = +0.5 and uses the distance modulus to get distance Cepheids – Obeys a Period-Luminosity Relation – One observes the period, looks up M in the chart to the right, observes m, and then applies the distance modulus WorldWide Telescope Exercise 5.1c – explore the Milky Way in different wavelength bands Galactic Rotation Curve Rotation Curve Explorer Andrea Ghez Clip Vera Rubin Site  Class 5.3 11/25/2022 Announcements Student Observatory open/clear tonight, closed rest of week Review Task on the Milky Way Peer Instruction on Galaxy Classification Exercise 5.3 Galaxy Classification Discussion of Galaxy Types Galactic Collisions Gravitas  Formative Assessment Task (on the Milky Way Galaxy) https://astro.unl.edu/newRTs/MilkyWayGalaxy/ https://astro.unl.edu/newRTs/MilkyWayGalaxy/ Well-randomized! Do a couple of times. Hubble Tuning Fork  Exercise 5.3b https://physics.unl.edu/~klee/GalaxyClassification/GalClass_07.html Galaxy Collisions  Gravitas Galaxy Dynamics by John Dubinski A combination of supercomputer simulations of galaxy collisions and contemporary music Gravitas is available for free download here There are 9 parts to gravitas – Part 2: Galactic Encounters is shown on the next page. Gravitas 2 on YouTube  Class 5.4 12/2/2024 Announcements – Participation scores – updated, but not weighted correctly yet – Pre Survey Scores/Post Surveys in progress PI: Wrapping up Galaxy Classification Exercise – Looking at Distant Objects – 10 minutes – Short play – 5 parts – will need 5 volunteers Exercise 5.4a Quasar Logic – Gravitational Lensing Demo – Gravitational Lensing ADV Flying through SDSS (Sloan Digital Sky Survey) Data  Looking at Distant Objects 2 pages (10 minutes) Class Play on Question 8 (there are 5 parts) – Part 1 – Earth – Part 2 – Star (100 Mly away) – Part 3 – Day 1 photon – sets speed of light – Part 4 – Day 10 My photon – takes off when 3 is 1/10 of the way to Earth – Part 5 – Day 50 My Supernova Photon – takes off when 3 is ½ of the way to Earth  Looking at Distant Objects #5 – Kids send a pic to Earth on their 12 birthday, good one for a formula Actual Age = 12 years + Star Distance in light-years #7 – Andromeda is 2.5 million ly away we see Andromeda as it was 2.5 million years ago #8 – a star is 100 million light-years away – We observe that it is 10 million years old – We expect that it will live 50 million years Birth 10My Exercise 5.4a Doppler Shift Quasar Logic Formula Hubble’s Law Must be farther away then lensing galaxy Inverse Square Law  Quasars The superluminous cores (supermassive black holes that are eating stuff) of distant galaxies  Gravitational Lensing Demo Please take a quick look at the gravitational lensing demonstration – See if you can view an “Einstein Ring” by looking right along the “eye-lens-ball” axis (your eye should be about 6 inches from the “lens”) – See if you can view irregular arcs by moving your eye a little off axis.  Class 5.5 4/19/2024 Announcements SSDS data fly through Exercise 5.4b A Review of Look-back time PI – Expansion of the Universe Smartphone Simulation: Hubble’s Law  Sloan Digital Sky Survey Fly- Through Look for …. ▪ Nearby galaxies == Normal Galaxies The black holes at their cores aren’t eating much ▪ Zones of avoidance – butterfly shape ▪ Distance bias – only see very luminous objects at large distances -- large red elliptical galaxies ▪ Quasars ▪ CBR – when the universe became transparent  SDSS ver 4 Things to look for: – Near by us – normal galaxies, we are not looking far back in time. – At 0:50 -- note when we get out a ways, we see really big red galaxies – these are giant ellipticals – At 1:20 -- note the butterfly shaped distribution of galaxies in space – At 1:30 -- we see the quasars – At 1:30 -- we see the CBR – note its structure – showing slight variations in temperature and density. – At 2:11 -- Stephanie Snedden  Exercise → LookBack Time 5.4b Universe Density →  Summation The Universe is Expanding! There is no center to the universe (nor an edge) – think coins on the surface of a balloon Look-Back Time dominates what is observed (from every location)! – Nearby normal galaxies – Further away -- more active galaxies – Quasars (only) at great distances – CBR Universe was smaller in the past and there was more interaction between galaxies back then – More spirals in the past – becoming ellipticals over time! Hubble’s Law vr = H 0 D  Expansion of the Universe (in Practice Exercises) Do the galaxies appear to get bigger? Compare the amount that the distance between the D and C galaxies changed in comparison to the amount that the distance between the D and E galaxies changed. What galaxy, C or E appear to have moved farther from D? Is there a center to the universe?  Smartphone Sim: Expansion of the Universe https://astro.unl.edu/mobile/G alaxies/GalaxiesStable.html Tasks 1) This sim show the velocity vectors for all other galaxies (besides yours). Verbalize how Hubble’s Law is demonstrated in the sim. 2) Move to a different galaxy (and then several more). How is Hubble’s Law different at these locations? Does it look different anywhere? 3) Is there a center in the simulation? Why?  Class 5.6 4/22/2024 Announcements – Exam 5 coming up – All Experiential Projects scored Peer Instruction over Hubble Constant Class Exercise 5.5a Hubble’s Law – Determining the Hubble Constant Exercise 5.6b Evolution of the Universe – Tau Zero – Famous Book – Runaway Universe Clip – “Dark Energy”  Class Exercise 5.5 (Determining the Hubble Constant) Error Bars There is uncertainty in our determination of the recessional velocity of a galaxy Some due to doppler shift in the spectra Most due to “peculiar velocities” – motion around the center of mass of a bound structure, especially for nearby galaxies Errors in distance Get larger with distance 5 (of 6 points are done for you) – add Bootes Plot point and draw in “error rectangle” Draw in a “best fit line” – H0 is the slope Not required to go through the origin, but easier! Draw in two lines (the most sloped and the least sloped) that still hit all of the error rectangles and determine their values of H0  (76000 km/s)/(1200 Mpc) =63.3 km/s-Mpc Recessional Velocity (1000 km/s) (66000 km/s)/(1220 Mpc) =54.1 km/s-Mpc (46000 km/s)/(600 Mpc) =76.7 km/s-Mpc Distance (Mpc)  Class Exercise 5.6b Evolution of the Universe  No Gravity Accelerating Open Flat Closed True Age Hubble Time Big Squeeze  Tau Zero (1970) Award-Winning (Serious) science fiction book by Poul Anderson Concerns “Time Dilation” – A well-researched area of physics known as special relativity – Time passes more slowly for clocks in motion A spaceship get traveling faster (and faster) and gets closer (and closer) to the speed of light – Which means that time passes very slowly – They witness the end (or beginning) of the universe  Video Clip NOVA Runaway Universe Short clip – 9:30 to 15:50 – Type I supernovae are fainter than astronomers expected Universe is expanding  Segment 5 Review Day 4/24/2024 Announcements – Take an exam, start segment 6 Review – Characteristics of Types of Galaxies – Hubble’s Law & Peculiar Velocities Exercise 5.6a – Specific Big Bang Details – Expansion, Inflation, CBR, Nucleosynthesis – WMAP Exercise 5.6c (summarizes segments 4 & 5) – How are elements produced? Exercise 3.3a Characteristics of Galaxies X Elliptical Galaxies are spheroidal by nature. The halo component of a spiral is also spheroidal. X Only spiral galaxies have a cylindrical disk. X O and B stars don’t live very long. Thus, only galaxies with active star formation like spirals will have them. X Many more K and M stars are formed than the more massive stars. They are also very long lived. Thus, they will be very common in both spiral and elliptical galaxies. X Since elliptical galaxies have no star formation, they contain only old stars. Old K and M stars appear red. X Spiral galaxies contain stars of all types and ages which gives them their white appearance.  X Only spiral galaxies have the gas and dust necessary for star formation. X Elliptical galaxies have a very large range of sizes, but the largest galaxies are elliptical as they are the merger of several galaxies X This galaxy would only recently have formed -- and almost all of the galaxies we observe have been around a while. X Elliptical galaxies are the most common. X Since spiral galaxies are the brightest because of their active star formation, we can see them to a greater distance than other galaxies. Thus, there is a large bias favoring their observation. X Everything in the universe (that is not gravitationally bound) obeys Hubble’s Law. X Ellipticals are likely to have been involved in collisions (which used up all of their gas and dust), while spirals have not been in collisions.  Smartphone Sim: Hubble’s Law https://astro.unl.edu/smartphone/HubblesLaw/ Questions Q1B, Q1C, Q1D, Q1E Q2A, Q2B This sim is at an early state! (Pinch/Zoom does not yet work.) Big Bang?  Class Exercise 5.6a Big Picture View of the Big Bang  Exercise 5.6 Directions t=0 Inflation 1) This exercise is organized around an axis The universe began in The universe drastically Big Picture showing the direction of increasing time. a state of … very high increases in size because of temperature and very …inflation. There was a Evolution Indicate the direction of increasing temperature and density as well. high density. The rapid change in size (from of the Universe 2) Enter facts in the 4 small boxes. universe was very small the size of an atom to that of 3) Pivotal events in the history of the and very simple -- no a cherry pit) due to the universe are labeled in 5 large boxes. complex structures separation (decoupling?) of Complete the explanatory paragraphs on existed. the fundamental forces. This these events that are started for you. solved many problems in the 4) Indicate on the time axis the approximate standard big bang model. location when the universe was half the age it is today. Most energy is in ½ age Time the form of Matter Today Most energy is in Age= Age=0 the form of Radiation 13.7 Gyr Element Building H, He, Li, & Be are produced, Recombination but nothing larger because … The universe has cooled to The early universe was hot there are no stable nuclei with the point where neutral enough so that energy could atoms can exist which either 5 or 8 particles in the change form between allows …the formation of nucleus and the deuterium matter and radiation very neutral atoms. Since bottleneck. Nuclei are easily. High energy photons electrons are now bound to Galaxies Form! increasing in size one nucleon produce particle-antiparticle protons they can only at a time but it is so hot that a pairs and vice versa. absorb photons photon has enough energy to First Stars corresponding to the break a nucleus apart. As A generation of very massive differences in their energy soon as it is cool enough for stars form and …quickly go levels -- where before they nuclei larger than deuterium supernovae distributing some could absorb any photon. to survive, it isn’t hot enough small amount of metals. Our Light could now travel to fuse more than one nucleon halo is low metallicity but it freely through the universe at a time and jump over the isn’t zero. These metals had and we see the light “freed” barriers at 5 and 8. to come from somewhere. at this time is the CBR. Recommended Demonstration Video “Shape Memory Allows” — shows a fun example of a phase change loosely analogous to “inflation” 854 x 480 px, 3.2 minutes  WMAP Spacecraft operating from 2001 to 2020 that studied the Cosmic Background Radiation – Structure of the CBR tells us about the density of matter at the time of recombination – Illustrates the “seeds” of galaxy formation Illustrated in the WorldWide Telescope – https://www.worldwidetelescope.org/webclient/ WMAP  Exercise 5.6c Exercise “Elements in the Universe” At this early time, much of the universe is Larger nuclei are constructed through Larger nuclei are constructed through in the form of radiation and there is a lot fusion reactions in the cores of stars. This fusion reactions in the cores of stars. This interchange between matter and is elements like C and O in small stars, but is elements like C and O in small stars, but radiation. But more matter and more elements like Mg, Ne, and up to Fe in the elements like Mg, Ne, and up to Fe in the complex matter forms over time as the most massive stars. most massive stars. temperature falls. Once nucleons exist, larger nuclei are constructed one nucleon at a time, but energetic photons initially break these larger nuclei apart. 56Fe is the most tightly bound nucleus. The binding energy per nucleon graph illustrates that we can only get energy out (and help support the weight of the star) through nuclear fusion reactions up until 56Fe. No stable nuclei with A = 5 or A = 8 Once it is cool enough for 2H to exist, it isn’t hot enough to overcome the coulomb barriers and jump the A = 5 and A = 8 gaps. WMAP What’s in the Universe?