CU-Boulder ASTR 1120 - Lecture Notes (34 pages)

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Lecture Notes



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Lecture Notes

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Lecture Notes


Pages:
34
School:
University of Colorado at Boulder
Course:
Astr 1120 - General Astronomy- Stars and Galaxies
Unformatted text preview:

ASTR 1120 General Astronomy Stars Galaxies FINAL Saturday Dec 12th 7 30pm HERE ALTERNATE FINAL Monday Dec 7th 5 30pm in Muenzinger E131 Last OBSERVING session Tue Dec 8th 7pm Please check your grade on clickers midterms HWs on CU learn e mail Thomas if you see discrepancies missing grade Review of the Course Four general topics 1 Intro Scales matter light telescopes 2 Stars 3 Galaxies 4 Cosmology Dark Matter Universe Course Goals To develop a broad view of what we know about the Universe To understand the forces that shape the Universe and its history To help you understand how we figured all this out To learn how science works 1 The Scale of the Universe Matter Atom electron nucleus p n protons neutrons e Light our main source of astronomical knowledge The Electromagnetic spectrum Thermal black body Spectra Emitted by all solid opaque objects including stars planets humans Smooth broad spectrum rising to a peak at some wavelength where most of the radiation is emitted Wien s Law Stefan Boltzmann Law Spectral lines By atoms emitting or absorbing PHOTONS light The energy change between levels is equal to the energy of the photon Rememberlarger energy jumps will be SHORTER wavelength photons Telescopes Refracting vs Reflecting Size matters Light gathering power Angular resolution diffraction limit Telescopes are built differently for different wavelengths ground based airborne and space Stars Starting with our Sun 1 2 3 4 5 6 What is the Sun made of How does the Sun produce its energy Which forces keep the Sun in equilibrium What s inside the Sun What will be the end of the Sun How massive is the Sun Stars Shine with energy released from fusion hydrogen fusing into helium Overall fusion rate very stable gravitational equilibrium Violent activity on the surface Measuring the Stars Estimating distances via parallax Inverse square law for brightness Apparent brightness and distance luminosity Measuring temperatures via color spectral type OBAFGKM Measuring masses via binary stars The Hertzsprung Russell Diagram The Main Sequence Stars spend most of their lives here More massive stars are Rarer Hotter Bluer Brighter Shorter lived Can estimate ages of star systems from main sequence turnoff Stellar Evolution 1 Star Birth 2 Main Sequence 3 Series of expansions and deflations in response to core nuclear burning Low mass stars Red giant Horizontal branch star Planetary nebula White dwarf Stellar Evolution 1 Star Birth 2 Main Sequence 3 Series of expansions and deflations in response to core nuclear burning Low mass stars Red giant Horizontal branch star Planetary nebula White dwarf High Mass Stars Very rapid sequence fusing heavier elements up to iron Core unsupported collapse Supernova explosion Blasts heavy elements back into space Neutron star or black hole remains Stellar Graveyard White dwarfs and the possibility of white dwarf supernovae Neutron stars possible pulsars Black Holes Detected only by their interactions Stellar Graveyard White dwarfs and the possibility of white dwarf supernovae Neutron stars possible pulsars Black Holes Detected only by their interactions Stellar Graveyard White dwarfs and the possibility of white dwarf supernovae Neutron stars possible pulsars Black Holes Detected only by their interactions 3 The Milky Way Galaxy Our home spiral galaxy Bulge Halo Disk Star Gas Star Cycle Gas Dust Stars A supermassive black hole in the Galactic Center Yes 3 The Milky Way Galaxy Our home spiral galaxy Bulge Halo Disk Star Gas Star Cycle Gas Dust Stars A supermassive black hole in the Galactic Center Yes 3 The Milky Way Galaxy Our home spiral galaxy Bulge Halo Disk Star Gas Star Cycle Gas Dust Stars Sgr A A supermassive black hole in the Galactic Center Yes Other Galaxies Main Galaxy types Spirals Ellipticals Irregulars Bulges spheroids Older Population II Disks Forming stars today Population I AGNs Central Engines How do AGNs emit so much light in so little space They are powered by accretion disks around supermassive black holes In some AGNs huge jets of material are shot out at the poles These jets are strong radio sources JET DISK Distance Ladder to measure universe Different standard candles are useful for different distances Discovery of an Expanding Universe Hubble s Law The distances between galaxies are getting bigger Running time backwards age of the universe Galaxy Evolution Galaxy formation Observe galaxies at different redshifts lookback times Assemble sequence Galaxy interactions Spirals Ellipticals Active and starburst galaxies Check via computer models of gas gravity and star formation 4 Cosmology Dark Matter Spiral galaxy rotation curves and galaxy clusters 3 ways suggest large amounts of DARK MATTER 90 of the universe is a type of matter we can t see Most likely candidate WIMPs Probably an unidentified subatomic particle The Fate of the Universe Hubble constant sets the expansion rate for NOW Dark matter pulls expansion curves downwards Upwards curve suggests DARK ENERGY pushing against gravity The Creation of the Universe Evidence for the Big Bang Expanding universe Cosmic microwave background H He content of the universe Inflation Carl Sagan Author of A Pale Blue Dot The Demon Haunted World Contact Cosmos We succeeded in taking that picture from deep space and if you look at it you see a dot That s here That s home That s us On it everyone you ever heard of every human being who ever lived lived out their lives The aggregate of all our joys and sufferings thousands of confident religions ideologies and economic doctrines every hunter and forager every hero and coward every creator and destroyer of civilizations every king and peasant every young couple in love every hopeful child every mother and father every inventor and explorer every teacher of morals every corrupt politician every superstar every supreme leader every saint and sinner in the history of our species lived there on a mote of dust suspended in a sunbeam I wish you good luck with the Final Exam please bring a 2 pencil and ID and I hope you ve enjoyed this course that has attempted to shed a little light on the Universe


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