Sample Questions ---------------- 1. Compared to a faint Cepheid, a more luminous Cepheid variable (a) does not change its size (radius) as it pulsates (b) has a longer pulsation period (c) changes its pulsation period every 22 years, instead of 11 years (d) does not pulsate at all (e) has a lower mass 2. Observations show that the rate of the expansion of the Universe is (a) decreasing (b) the same as it was billions of years ago (c) increasing (d) uncertain and is a matter of debate (e) unknown 3. The distance to nearby galaxies be measured using (a) radar ranging (b) parallax (c) Cepheids (d) all of the above (e) none of the (a)-(c) 4. The distance to where the Cosmic Microwave Background Radiation was emitted can be measured using (a) radar ranging (b) parallax (c) Cepheids (d) all of the above (e) none of the (a)-(c) 5. Elliptical galaxies (a) travel in elliptical orbits around the center of our Galaxy (b) is the class of galaxies that the Milky Way belongs to (c) can form as a result of a collision between galaxies (d) contain a lot more dust than spiral galaxies (e) is another name for Globular star clusters TOPICS ------ Stellar remnants: white dwarfs, neutron stars, black holes; approximate mass ranges of progenitor stars and remnants, what supports them against gravity White dwarfs in binaries: nova and supernova explosions; the 1.4 solar mass limit. White Dwarf SN as distance indicators. Neutron stars; pulsars; X-ray binaries. Relativity: the two starting points of relativity; predictions The Milky Way Galaxy: approximate scaling; structure of the MW Differential rotation in the disk; spiral arms; dust obscuration; 21 cm line of Hydrogen and its importance in studying the galaxy Formation of the MW galaxy; the role of angular momentum; the disk; the distribution of globular star clusters; chemical enrichment The very center of the Galaxy; orbits of stars around the supermassive black hole. Galaxies: 3 types: most are spirals and ellipticals, some irregulars; their general characteristics; galaxy collisions; clusters of galaxies Measuring distances in astronomy: radar ranging, parallax, main sequence fitting, Cepheids and other variable stars (period-luminosity relation). MS fitting and Cepheids can be used for nearby galaxies. Hubble Law; recessional velocity is proportional to distance to the galaxy; expansion of space; Cosmological Principle. Age of Unvierse from Hubble constant. Other measurements of the age of the Universe Dark Matter: rotation curves of spiral galaxies, motions of stars within elliptical galaxies, gravitational lensing, hydrostatic equilibrium of hot gas in galaxies' halos. Measurements in clusters of galaxies. Dark matter candidates/possibilities: neutrinos, modifications of Newton's/Einstein's theories, elementary particles. Large scale structure of the Universe: clusters, filaments, walls, voids. Evolution of structure, the role of gravity. Expansion history of the Universe: without dark energy, there are 3 possibilities; there is a 1-to-1 correspondence between global geometry and matter content. Evidence from white dwarf supernova; the accelerated expansion. Model of our Universe: dark matter, ordinary matter and dark energy contributions. The future of expansion. History of the Universe: gets denser and hotter towards earlier times; the earlist time that can be studied; Big Bang Nucleosynthesis, production of Helium; Cosmic Microwave Background Radiation, detection of these photons today. CMB and thermal radiation; temperature fluctuations in the CMB and their relation to the distribution of galaxies today. Global geometry of the Universe from the CMB. Inflation; three observations not explained by the model: origin of the large scale structure of the Universe, uniformity of the large scale structure, why the global geometry of the universe is flat. How early inflation accounts for these. Olber's paradox and the finite age of the Universe.