AST 320 – Introduction to Astrophysics (2015)


M3 in AB88, F12 in AB 114
Marten van Kerkwijk, MP 1203B, 416-946-7288,; office hours: after class, or by appointment
Teaching assistant
Elliot Meyer, AB 206A, 416-978-7123,; office hours: W12
Web page
Lecture notes
1-4, 5-9, 10-13, 14-16, 17-18
Mini problem sets
by due date: Jan 9, Jan 13, Jan 16, Jan 23, Jan 26, Feb 2, Feb 6, Feb 9, Feb 13, Mar 2, Mar 16, Mar 20; Cosmology: 1, 2, 3, all due last class, March 30th!
Previous midterms
2005, 2006, 2007, 2009, 2014
Previous finals
2005, 2006, 2007, 2009, 2014

Note on e-mail: both your teaching assistant and professor will try to answer e-mail within one working day. For questions about the problem sets, please come to the TA office hour; please do not expect that e-mails sent in the weekend will be answered before class on Monday.


This course aims to teach the physics underlying the formation, the equilibrium, and the evolution of structure on all astronomical scales. Two main topics will be discussed:


  • Hydrostatic equilibrium, virial theorem;
  • Collapse of molecular clouds, star formation;
  • Equation of state in stellar interiors;
  • Simple stellar models: polytropes;
  • Radiative energy transport, opacity sources;
  • Convective energy transport;
  • Hayashi track; pre–main sequence evolution;
  • Energy balance: contraction, nuclear fusion;
  • Stellar model building;
  • The main sequence, brown dwarfs;
  • Low-mass stars: giant phases, shell burning;
  • High-mass stars: fusion up to iron;
  • Supernovae.

The Universe

  • Cosmological principle, basic parameters;
  • Simple relativistic cosmology;
  • Big Bang nucleosynthesis;
  • Times, distances, horizons, diameters;
  • Cosmic microwave background, inflation;
  • Fluctuations and structure formation.

Course text book

The text book is An Introduction to Modern Astrophysics, 2nd edition, by Carroll & Ostlie (Addison Wesley, 2006). The focus will be on chapters 9, 10, 12, 13, 15, and 16 (Stars), and 29 and 30 (Universe). A more detailed list will be given in class. Furthermore, handouts will be made available that summarise the material and give additional detail where the text does not go into sufficient depth.

Advanced texts

Stellar Structure and Evolution, by Kippenhahn, Weigert & Weiss (Springer-Verlag, 2012); a very good book (recommended by many of the former students of AST 320) for those who want to delve deeper into the subject.


The course prerequisites are AST 221H & 222H, and PHY 252H (the latter can be taken concurrently). These are equivalent to parts of the text book, which will be mentioned explicitly in class.


  • (32%) Mini problem sets, with one due (almost) every class.
  • (8%) Presentation on one of the mini-problems.
  • (20%) Term test, in class on March 6th.
  • (40%) Final examination.

Note: as announced by e-mail, if the final is made better than the midterm, it will get 60% weight, and the midterm will be ignored.

Mini problem sets

At the start of almost every lecture, there will be a mini problem set due, which uses material already discussed to prepare for the lecture. These mini problem sets will be available at least one week beforehand (except the first one).

As indicated by the name, the mini problem sets are meant to be short, requiring no more than two hours of work, and the answer should easily fit on the page with the question. If you seem to need more time or space, you are problably making things too complicated, and should come to an office hour!

Since mini-problem sets are discussed at the start of the same lecture at which they are due, no credits will be given for anything handed in too late. However, the final grade will be based ignoring the three worst marks; hence, you can afford to miss three (but I recommend you keep these in reserve, e.g., in case you get ill).


Each student should pair up with another to discuss one mini problem set at the start of a lecture. The discussion should focus on the physical interpretation and astronomical context, not on derivations, and should last no more than 12 minutes (including discussion, so prepare for about 8 minutes). You are strongly encouraged to check with the professor what you intend to discuss in class.

Author: Marten van Kerkwijk

Created: 2015-03-21 Sat 16:51

Emacs 24.4.1 (Org mode 8.2.10)