C1 Astrophysics : Trinity
Term 2016.
Atomic Processes and the Interstellar Medium
Patrick Roche
This part of the course describes how quantitative information on physical conditions in diffuse matter and element abundances is obtained through analysis of spectroscopic observations
The
synopsis for the lectures is:
„Astronomical spectroscopy, lines in different spectral regions, atomic
physics and selection rules, forbidden and allowed transitions
„The two level atom, A, B and C coefficients and their useful regimes,
thermal populations,
IR fine structure lines, critical density, mass estimates
„Recombination and ionization processes, the Stromgren
sphere, ionization balance, effective temperature estimates.
„The 3 level atom: diagnostics of electron temperature and electron density.
„Absorption lines, equivalent width and the curve of
growth. Column densities and abundances
„The interstellar medium. Atomic and ionic
absorption lines, abundance of gas, molecules and dust. Hyperfine transitions: 21cm line of H,
Galactic structure
„Interstellar extinction, dust components, thermal emission, equilibrium
and stochastic processes
„The sun. Ionization and
sources of opacity, radiative transfer, the Gray
atmosphere, limb darkening, absorption line formation
There will be two
classes covering this material, and handouts are available here
There are many text books that cover this material, but good recent sources are:
Physics & Chemistry of the Interstellar Medium,
by Sun Kwok (University Science Books, Sausalito,
California) ISBN-10: I-891389-46-7
Note that the second half of the book goes into
much more detail than can be covered in the 8 lectures provided in C1.
Or
Physics of the Interstellar and Intergalactic
Medium, by Bruce Draine.
(Princeton University Press) ISBN-10: 0691122148