AST 393F

SURVEY OF THE INTERSTELLAR MEDIUM

Instructor: Harriet Dinerstein

Semester: Spring 1997

Meeting Times: TTh 9:30-10:45 a.m.

Unique No: 42320

GOALS: The purpose of this required ("core") course for first- and second-year astronomy graduate students is to provide a broad overview of the interstellar medium. I intend for it to serve as a general introduction for those who are considering doing research in this field, but it should also give others enough background to be an informed audience for talks and papers on this field.

TEXTS: Essentially, my course notes are the textbook. Spitzer's Physical Processes in the ISM (1978) is still the most complete general reference book available, but it is organized into chapters by physical process, whereas I prefer to structure the course around major components of the ISM: which reactions and processes are important in each, and how we study them. Several copies of Spitzer have been ordered by the UT Co-Op. Also, it and several other useful books will be on reserve in both the Péridier and PMA libraries (and can be checked out from the latter for three days).

COURSE WORK: There will be of order 5-6 problem sets, mostly concentrated in the first half of the semester, worth about 25% of the grade. A midterm will be given in class, probably the week after spring break, for 20%, and a comprehensive final exam during finals week, worth 25%. The rest of the grade will be based on oral presentations to be scheduled in mid-April and the written course notes for these presentations, plus a short (1-2 page) standard-format research proposal, which can be on the same topic as the oral presentation if the student wishes.

OUTLINE (subject to revision):

Overview and history of the subject; choice of physical parameters, excitation and ionization equilibria, the interstellar radiation field; global steady-state models, the multi-phase ISM
Physics and Observables of the Major Phases and Components
1. H I Regions
  Optical and UV Absorption Lines: Curve-of-growth methods, gas-phase depletions; 21-cm Line: radiative transfer, galactic 21-cm surveys
2. H II Regions
  Ionization Structure and Strömgren spheres; Thermal structure, collisionally excited lines; Recombination Emission; T and n diagnostics, ionic abundances
3. Molecular Clouds
  Radiative transfer for mm-wave lines (CO), line excitation and kinetic temperatures, mass estimates; the H₂ Molecule -- formation and destruction, UV absorption and IR emission lines
4. Interstellar Dust
  Extinction Curve, grain properties; Interstellar polarization; Grain heating and emission; Origin and evolution of grains
5. Hot Phases
  The Galactic halo, etc.; X-rays and supernova remnants; the "Reynolds" layer
Distribution of the ISM
1. The Local ISM and the local "hot bubble"
2. Large-scale distribution of the ISM in our Galaxy: scale heights, H I vs. H₂ radial distribution, results from gamma rays
3. "Texture" of the ISM -- global models revisited; filling factors, "porosity," vertical structure
The ISM of Other Galaxies

GOALS:	The purpose of this required ("core") course for first- and second-year astronomy graduate students is to provide a broad overview of the interstellar medium. I intend for it to serve as a general introduction for those who are considering doing research in this field, but it should also give others enough background to be an informed audience for talks and papers on this field.

TEXTS:	Essentially, my course notes are the textbook. Spitzer's Physical Processes in the ISM (1978) is still the most complete general reference book available, but it is organized into chapters by physical process, whereas I prefer to structure the course around major components of the ISM: which reactions and processes are important in each, and how we study them. Several copies of Spitzer have been ordered by the UT Co-Op. Also, it and several other useful books will be on reserve in both the Péridier and PMA libraries (and can be checked out from the latter for three days).

COURSE WORK:	There will be of order 5-6 problem sets, mostly concentrated in the first half of the semester, worth about 25% of the grade. A midterm will be given in class, probably the week after spring break, for 20%, and a comprehensive final exam during finals week, worth 25%. The rest of the grade will be based on oral presentations to be scheduled in mid-April and the written course notes for these presentations, plus a short (1-2 page) standard-format research proposal, which can be on the same topic as the oral presentation if the student wishes.