Astro 622 Interstellar matter

Course outline
Gareth Wynn-Williams

  1. Introduction
    Grading, textbooks, etc
  2. Overview of ISM
    Phases, properties of gas and dust, distribution of ISM
  3. Observing the ISM
    Techniques available at all wavelengths
  4. Ionization
    Photoionization & recombination of hydrogen and other elements, HII regions, Stromgren spheres, partially ionized regions, collisional ionization.
  5. Recombination Radiation
    Visible & radio recombination lines of hydrogen and other elements, free-free radiation, bound-free radiation. Determining properties of HII regions from radio continuum data
  6. Forbidden line Emission
    Multi-electron ions, collisional excitation, determining temperatures, densities and abundances in HII regions, thermal balance in HII regions
  7. The 21-cm line
    Basic radio astronomy, emission and absorption, , rotation curves of the Galaxy, kinematic distances, measuring masses of HI in galaxies. estimating gas temperatures, introduction to phases of ISM.
  8. UV & visible interstellar absorption lines
    Curves of growth, equivalent widths, Copernicus HI studies, molecular hydrogen, interstellar abundances & depletion, diffuse interstellar bands.
  9. Interstellar chemistry
    Molecular hydrogen, formation and destruction of molecules grain surface and gas phase chemistry, PAH molecules.
  10. Absorption and emission from molecular gas
    Observations of mm CO emission, optical depth and excitation effects, cloud models, LVG codes, use of isotopes, high density tracers, determining physical conditions in clouds. Typical properties of molecular clouds. Interstellar masers.
  11. Interstellar extinction
    Dust extinction, reddening, IR and UV properties, scattering and albedo, exceptions to thin-screen model, gas-dust correlations, X-ray absorption. Polarization of starlight
  12. Radiation from dust
    Thermal equilibrium of dust grains, VSGs and PAH emission. Lyman-alpha heating of dust within HII regions, dust inside the Solar System.
  13. The nature and evolution of dust grains
    Size of dust grains from extinction curve, Dust spectral features, abundance considerations. Origin of dust grains, carbon-rich and oxygen rich stars, destruction processes, sputtering, interstellar grains within the Solar System, interplanetary dust.
  14. Interstellar Magnetism
    Nature of interstellar magnetic field, flux freezing, ambipolar diffusion, Zeeman effect, Alfven waves, interstellar polarization.
  15. Shock Waves
    Sound speed, jump conditions, ionization fronts, radiation from shocks, Coronal lines, X-ray emission. IR molecular hydrogen emission
  16. Cosmic Rays
    Energy spectra, composition, propagation, scattering, lifetime in Galaxy, gamma ray production,
  17. Synchrotron radiation.
    Single particle radiation, power laws, polarization, energy losses, self-absorption, supernova remnants, galactic background
  18. Radio Propagation through ISM
    Plasma frequency, low frequency absorption, pulsar dispersion, Faraday rotation, Faraday depolarization, interstellar scintillation
  19. Heating, cooling and phases of ISM
    Cooling processes in molecular, atomic and ionized gas, Heating processes, pressure balance, thermal instabilities, shock heated gas, models for interstellar clouds, photo-dissociation regions.
  20. Galactic Distribution of interstellar gas
    Scale heights, Oort limit, thickness of gas distributions in the Galaxy, large-scale structure of HI, distribution of molecular clouds, spiral arms, diffuse ionized gas, gas in the halo, high velocity clouds, Galactic Center.
  21. Interstellar matter near the Sun
    Local bubble, interplanetary medium, solar wind, heliopause, Lyman-alpha backscattering, helium wake.
  22. Gravity and Stability
    Jeans length, fragmentation, Parker instability, stability of molecular clouds, virial mass, spherical collapse, rotation, formation of disks
  23. Star forming regions
    Molecular cores, low mass star formation, bipolar flows, clustering, high mass star formation, triggered star formation.
  24. Origin and fate of interstellar matter
    Mass loss stars, planetary nebulae, Supernovae, evolution and balance of interstellar medium
  25. Interstellar gas in other galaxies
    ISM in Ellipticals. Differences in spiral gas content along Hubble sequence. Starbursts, AGNs. Emission line diagnostics

    Gareth Wynn-Williams (wynnwill@ifa.hawaii.edu)