Stars, Galaxies, and Beyond Summary of notes and materials related to University of Washington astronomy courses: ASTR 322 The Contents of Our Galaxy (Winter 2012, Professor Paula Szkody=PXS) & ASTR 323 Extragalactic Astronomy And Cosmology (Spring 2012, Professor Željko Ivezić=ZXI). Summary by Michael C. McGoodwin=MCM. Content last updated 6/29/2012 Rotated image of the Whirlpool Galaxy M51 (NGC 5194)1 from Hubble Space Telescope HST, with Companion Galaxy NGC 5195 (upper left), located in constellation Canes Venatici, January 2005. Galaxy is at 9.6 Megaparsec (Mpc)= 31.3x106 ly, width 9.6 arcmin, area ~27 square kiloparsecs (kpc2) 1 NGC = New General Catalog, http://en.wikipedia.org/wiki/New_General_Catalogue 2 http://hubblesite.org/newscenter/archive/releases/2005/12/image/a/ Page 1 of 249 Astrophysics_ASTR322_323_MCM_2012.docx 29 Jun 2012 Table of Contents Introduction ..................................................................................................................................................................... 3 Useful Symbols, Abbreviations and Web Links .................................................................................................................. 4 Basic Physical Quantities for the Sun and the Earth ........................................................................................................ 6 Basic Astronomical Terms, Concepts, and Tools (Chapter 1) ............................................................................................. 9 Distance Measures ....................................................................................................................................................... 9 Time Measures ........................................................................................................................................................... 10 Sky Position, Coordinate System, Motion and Rotation, Ecliptic, and Sidereal Terms .................................................. 12 Celestial Mechanics (Chapter 2) ...................................................................................................................................... 15 Kepler’s Original Laws of Planetary Motion .................................................................................................................. 15 Laws of Gravity and Motion......................................................................................................................................... 16 Light Properties (Pre-QM and Early QM); Distance and Magnitudes (Chapter 3) .............................................................. 18 Astronomical Distance, Luminosity, Magnitude ........................................................................................................... 18 Magnitude and Distance Modulus ............................................................................................................................... 19 Light (Photon) Wave vs. Particle Properties .................................................................................................................. 20 Color and Color Index ................................................................................................................................................. 25 The Special Theory of Relativity (Chapter 4, omitted) ...................................................................................................... 28 Quantum Properties of Light and Matter; Spectroscopy (Chapter 5) ................................................................................ 28 Spectroscopy .............................................................................................................................................................. 28 Light Interactions and Atomic Models ......................................................................................................................... 29 Quantum Mechanical Considerations ......................................................................................................................... 31 Telescopes (Chapter 6) .................................................................................................................................................... 33 Binary Systems and Stellar Parameters (Chapter 7) ........................................................................................................ 35 Mass Determination Using Visual Binaries.................................................................................................................. 35 Eclipsing Spectroscopic Binaries ................................................................................................................................. 36 The Classification of Stellar Spectra (Chapter 8) ............................................................................................................. 39 Harvard Classification................................................................................................................................................. 39 Statistical Mechanical Considerations ......................................................................................................................... 40 The Hertzsprung-Russell (H-R or HD) Diagram ........................................................................................................... 44 Stellar Atmospheres (Chapter 9, omitted)........................................................................................................................ 49 The Interiors of Stars (Chapter 10).................................................................................................................................. 50 Basic Equations .......................................................................................................................................................... 50 Energy Transport and Thermodynamics ...................................................................................................................... 55 The Main Sequence ..................................................................................................................................................... 57 The Sun (Chapter 11) ..................................................................................................................................................... 59 The Solar Interior ........................................................................................................................................................ 59 The Solar Atmosphere ................................................................................................................................................. 61 Miscellaneous Solar Topics ......................................................................................................................................... 66 Solar Cycle and Miscellaneous Variable Solar Activity ................................................................................................. 67 The Interstellar Medium; Protostar and Early Star Formation (Chapter 12) ..................................................................... 70 Interstellar Dust and Gas............................................................................................................................................ 70 Protostars ................................................................................................................................................................... 73 Pre-Main-Sequence Evolution, Young Stellar Objects, and the ZAMS .......................................................................... 78 Main Sequence and Post-Main-Sequence Stellar Evolution (Chapter 13) ......................................................................... 86 Evolution of the Main Sequence .................................................................................................................................. 86 Late Stages of Stellar Evolution (Post-Main Sequence) ................................................................................................. 90 Stellar Clusters ........................................................................................................................................................... 94 Stellar Pulsation (Chapter 14) ......................................................................................................................................... 97 Key Observations of Pulsating Stars ............................................................................................................................ 97 The Physics of Stellar Pulsation .................................................................................................................................104 Modeling Stellar Pulsation .........................................................................................................................................106 Nonradial Stellar Pulsation ........................................................................................................................................107 Helioseismology and Asteroseismology .......................................................................................................................109 The Fate of Massive Stars (Chapter 15) ..........................................................................................................................110 Post-Main Sequence Massive Stars That Evolve To Supernovae ..................................................................................110