AST 3047 TOPIC LIST 3
- colors of stars: ideal radiator and relation between color and temperature and
between brightness per unit area and temperature; interstellar reddening
- Hertzsprung-Russell (H-R) diagram: absolute magnitude; origins; regions,
terminology and connection among L, T, and R; white dwarfs
- atomic physics and spectra: Bohr model, excitation and ionization,
Saha ionization formula, hydrostatic equilibrium and pressure effects;
Payne and Harvard sequence; Kohlschuetter and Adams spectroscopic parallax;
Morgan-Keenan luminosity classes
- stellar evolution: Lockyer's scheme; Russell and evolution in the H-R diagram,
evolutionary tracks; radiative equilibrium and opacity; stellar masses (visual,
eclipsing+DLSB's); Eddington, gas vs. radiation pressure in hydrostatic equilibrium,
mass-luminosity relation, ionization and ideal gas law, energy sources; Trumpler's
classification of galactic cluster H-R diagrams; Vogt-Russell Theorem; Stroemgren
and hydrogen content; Kuiper's cluster H-R diagrams; Gamow and "tunnelling"; p-p
chain (Critchfield), CNO cycle (Bethe, von Weizsaecker)
- white dwarf stars: electron degeneracy (Fowler); Chandrasekhar's mass-radius
relation and limiting mass; gravitational redshift from general relativity;
gravitational collapse (Milne)
- interstellar dust: dark clouds (Barnard); reflection nebulae -- spectra,
color; reddening, extinction (Trumpler and galactic clusters); "zone of
avoidance" (Hubble)
- interstellar gas: absorption lines (Hartmann, Eddington), multiple lines
- gaseous nebulae: Hubble's dichotomy -- star spectra; Stroemgren's theory
of H II regions, photoionization and recombination, Zanstra temperature and
magnitude difference; "forbidden" lines (Bowen)
- stellar statistics: star counts, basic equation (K. Schwarzschild);
"Kapteyn Universe"; Plan of Selected Areas
- distances of globular clusters: period-luminosity relation for Cepheids,
Shapley and "cluster variables" (RR Lyrae stars, related to Cepheids)
- "Great Debate": protagonists, main issues and arguments, approximate date;
resolution of "island universes" question (Hubble using Cepheids)
- stellar motions in Milky Way: two-stream hypothesis (Kapteyn),
ellipsoidal hypothesis (K. Schwarzschild); "high-velocity" stars (B.
Lindblad); differential galactic rotation (Oort)
- morphological classification of galaxies (Hubble): types, diagram,
characteristics -- integrated color and spectral type
- masses of galaxies: rotation curve, virial theorem for cluster;
"missing mass" problem (dark matter)
- expansion of Universe: early radial velocities of spirals (Slipher,
Wirtz); Hubble and Humason, Hubble Law; general relativity and cosmological
models -- Einstein, de Sitter, Lemaitre, Friedmann; age problem;
nature of expansion and cosmological principle
- supernovae: collapse until supported by neutron degeneracy pressure,
release gravitational potential energy (Baade and Zwicky); search using
small Schmidt camera (Zwicky); two types and characteristics (Minkowski);
theory of neutron stars (Oppenheimer and Volkoff)
- radio astronomy: Jansky and beginnings, galactic center; Reber first
"dish" and mapping
- Pluto: "predictions" of Lowell and W. Pickering; discovery (Tombaugh),
characteristics
- instruments: large reflectors (examples), silver-on-glass mirrors, prime
focus, coude, coma; portrait camera, astrograph; Schmidt camera; objective prism;
selenium cell (Stebbins), photoelectric photometer
- observatories: Mt. Wilson, Palomar