Ay126: Interstellar Medium
There is no single book that can cover both pedagogy and at the same
time the astrophysics of ISM. Draine (Physics of the Interstellar and
Intergalactic Medium) does a very good job on the latter.
I will make use of a variety of sources for pedagogy. I would recommend
that you buy a copy of Draine's book. Below "Chapter" refers to appropriate chapter in Draine's book.
lists the errata and has problem sets and figures used in the book.
Astronomical spectroscopy : an introduction to the atomic and molecular physics of astronomical spectra by Jonathan Tennyson
Astrophysics of gaseous nebulae and active galactic nuclei by Donald E. Osterbrock, Gary J. Ferland
Atomic energy levels and Grotrian diagrams, vol. 1-4 by Stanley Bashkin and John O. Stoner, Jr
Introduction to atomic spectra by Harvey Elliott White
J"orn Wilms, Erlangen-Nuremberg. Nice site of notes related to high
energy astrophysics and atomic processes. Look under teaching (e.g. Astrophysical
collection, particularly good for X-ray astronomy.
HOMEWORK POLICY: You are free to discuss amongst yourselves. In fact, much
of learning is peer-to-peer. Brain storming is good.
However, true understanding comes from within and
so there is a delicate balance between communal problem solving and deep
contemplation. The latter will stand you in good stead.
I suggest the following approach: do your best to solve the homework. Sometimes
you simply cannot make a headway. Those problems are grist to group discussions.
Please include the sole undergrad in your discussions.
What you submit
must your own work (typed, written, programmed, drawn).
Two third will be determined by homeworks. The remaining one third will be
a final exam. We need to discuss options.
VENUE & TIME: We meet in room 126, Cahill as follows: Tuesday 1-2p, Thursday 1-2 pm
and Friday 1-2pm. The slot Monday 11a-12n is reserved for "backup" (I expect
to miss 4 classes owing to unavoidable travel). The notation is as follows:
"&" for classes that are makeup and "*" for the time I can meet any of you
and review the material taught the previous week.
FINAL EXAM.You will be given a list of questions by Friday morning.
The final exam can be found
Please sign up with the TA for "slots" (during the final exam week).
- Introduction I (April 4)
Constants that you should know.
From early Universe to present universe.
Dark Matter Simulation (Steinmetz) .
Simulation with gas (Hopkins) Red is million degrees
gas, green is 10^4 to 10^5 K gas and magenta is cold gas.
- Introduction II (April 6)
Pictorial introduction continued.
Phases of ISM. Mass Flow. The curious equipartion of energy densities.
The ionization potential of hydrogen is 13.6 eV. The optical
depth for photons above this energy is very large. Thus
elements and ions with ionization potential above 13.6 eV
will not be ionized. Bearing this mind review
Ionization chart  |
|   due COB (TA's desk) April 13.
- Atomic Spectra: The Beginnings (April 7)
Kirchoff, Balmer, Rydberg, Hydrogen Spectrum, Alkali spectra
(notation of spectral lines, SPDF).
SRK summary of Bohr & Schrodinger Model.
For next class, please review Schrodinger solution.
You may wish to read
Hydrogen Wave functions (UMich, Chem461).
For the advanced student I suggest, in addition, Schrodinger Model (UW Physics 2217).
- Orbitals, Periodic Table, Gross Structure (April 13)
SRK notes on Orbitals & Periodic Table.
Additional notes on the Periodic Table
(U. Wisconsin Chem461).
SRK summary of Alkali Spectra
& Clue to Gross Structure (splitting
of energy states due to angular momentum)
A very useful and beautiful
- Fine Structure, Spectroscopic Notation & Hund's rule (April 14)
SRK notes on the development of
the concept of fine structure
Relativistic Corrections and spin-orbit coupling.
Please read pages 1-7
SRK notes on LS Coupling
HomeWork 2   |   Due COB
(TA's desk) April 24   |
Grotrian diagrams for elements of astrophysical interest
Stancil's presentation on Fine Structure Lines
For the curious student: Sci Am article on the detailed spectrum of hydrogen
For the advanced student: In depth review of H atom
- Selection Rules, Helium Spectrum, Radiative Transfer (April 18)
Review Helium in view of Selection Rules. Radiative transfer (Chapter 7 of Draine's book)
- Basic Radiative Transfer, Einstein A&B Coefficent &Masers (April 20)
Chapters 6, 7
- HI emission & absorption, Galactic Distribution of HI (April 21)
Chaper 8  |  SRK notes
- Excitation and De-excitationn Rate Coefficients (April 24&; Makeup)
- Critcal Density & Results from Herschel (April 25)
Chapter 17  |  SRK notes
HomeWork 3   |   Due COB
(TA's desk) May 2   |
- Warm Ionized Medium (April 27)
- Fine Structure in WIM (RISS, DISS) (April 28)
Chapter 11   |   Lecture given by Harish Vedantham.
Vedantham Notes   |
- Photoionizaton (May 2)
Extreme Scattering Events Vedantham Notes
Review Saha equation, derive Milne relation.  |
Relate A coefficient to photon-absorption cross section.   |
- Hydrogen & Helium Recombination (May 4)
Oscillator strength  |  Case A & Case B  |
spectrum (Draine, Figure 10.2)
Radiative recombination of Helium  |
Grotrian diagram for Helium (Draine, Figure 14.3)
- HII regions (May 5)
Chapter 15 & 27
Stromgren sphere  |  Timescales  |  Thermal balance
Metal poor & Metal rich:
Cooling (density dependence)
HomeWork 4  |  Due COB, May 15
Solution by I. Escala
|  Additional constraint
on density of intervening nebula by measurements of precise arrival time.
- Hot Ionized Medium: Halo & Circumgalactic Medium (May 9)
Presentation: Studying Halo via HI, optical, UV & X-ray lines
Reading: Putman et al. review on Galactic Halo
Gupta et al. review on Hot Halo (X-rays)
Circumgalactic Medium of M31  |
- Collisional Ionization Equilibrium & CIE Cooling Curves (May 11)
Chapter 13, 34
Key Point: (1) New processes that become important at high temperatures and (2)
Collisional Ioinzation Equilibrium (CIE)
Auger & Dielectronic Recombination
Ionization states under CIE (Review Figures 2-38)
- Ionization & Cooling timescales (May 12)
Chapter 34 (Approach to CIE)
Reading Material: Smith & Hughes (2010)
- Collisonless Shocks (May 16)
Balmer dominated shocks (BDS):Model of Chevalier & Raymond
Review & Reading:
Review by Ghavamian
Review by Heng
in Herbig-Haro shocks
Useful Atomic data
- Dust I (May 18)
Chapter 21 (Observed Properties of Dust)  |
Draine IPMU Lecture 1
Additional Material: Lecture on
Dust by L. Hillenbrand
HomeWork 5  |  Due COB, May 25
- Molecules I: (May 19; Hillenbrand)
- Molecules II: (May 23; Hillenbrand)
- Molecules III: (May 25; Hillenbrand)
- Star-formation (May 26; Hopkins)
- Dust II (May 30)
- Purcell limit. Importance of C, Si. PAH, Mass Absorption Coefficient.
- Recapitulation: Propagation of waves in dielectric & conducting medium. Complex dielectric
- Dust III (June 1)
Big Particles (Babinet's theorem)  |  Small Particles: Rayleigh Scattering
Draine IPMU Lecture 2
- Dust IV, Cosmic Rays (June 2)
Heating (Chapter 25)
Cosmic Rays: Why we care about Lowest Energy Cosmic Rays?
Hydrogen by Cosmic Rays
ISM & Astrochemistry