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Astronomy 310 - Stellar Astrophysics

  1. Basic Information
  2. Course Overview
  3. Reading
  4. Software
  5. Assignments & Exams
    1. Homework
    2. Mid-Term Exam
    3. Final Exam
  6. Grading
  7. Syllabus & Schedule
  8. Animations
  9. Notes

Basic Information

  • Instructor: Professor Rich Townsend
  • Contact:
    • Phone: (608) 262 1752
    • Office: 4514 Sterling Hall
    • Email: townsend AT astro DOT wisc DOT edu
    • Mailbox: 5th floor, Sterling Hall
  • Times/Location: 09:55 am – 10:45am, Mon, Wed, Fri in Sterling 6515
  • Website: You're already here!
  • Office hours: Mon, Fri 11:00 am – 12:00am, other times by appointment

Course Overview

Stars are the fundamental building blocks of the Universe. They are the principal source of electromagnetic radiation at many wavelengths, including visible light. By injecting vast amounts of energy and momentum into their surroundings, they act as drivers for the evolution of their host galaxies. Likewise, through their creation of chemical elements heavier than hydrogen and helium, they are ultimately responsible for the existence of life as we know it.

Stellar astrophysics — the study of the appearance, structure, composition, and evolution of stars — is one of the resounding successes of modern physics. It brings together elements from almost every sub-field of physics (from atomic and nuclear physics, through to classical mechanics and relativity), allowing us to understand in surprising detail what goes on deep inside an object that, to us, is a mere pinprick of light in the sky.

This course is aimed at junior or senior majors in Astronomy or a related area, and is divided into three main components:

  1. Stellar Observations: how do we quantify the basic parameters of stars (position, distance, brightness, spectrum, etc)?
  2. Stellar Atmospheres: how does radiation interact with matter at the surfaces of stars, to produce the observables we measure?
  3. Stellar Interiors: what processes determine the interior structure, composition and evolution of stars?


The textbook for the course is An Introduction to Modern Stellar Astrophysics (2nd edition), by Ostlie & Carroll. We will cover most, but not all, of the chapters in the book, and the bi-weekly assignments will be based mainly on the problems given at the end of each chapter. Other books that will be occasionally referenced are as follows:

  • Stellar Structure and Evolution, by R. Kippenhahn & A. Weigert. A very thorough advanced undergrad/grad-level text that covers most of the details of stellar interiors.
  • Structure and Evolution of the Stars, by M. Schwarzschild. An introduction to stellar interiors, not quite as in-depth as Kippenhahn & Weigert, but rather more gentle.
  • Stellar Atmospheres, by D. Mihalas. The standard reference text on stellar atmospheres and radiative transfer.
  • The Internal Constitution of the Stars, by A. Eddington. One of the easiest-to-read and most insightful books on stellar structure, by the father of modern astrophysics.

All of these books are on reserve in the Astronomy library, apart from the last which can be found in the Physics library.


Apart from various simple cases, calculating stellar interior models requires a computer program. For the purposes of the class, I've created an on-line structure and evolution program, EZ Web, which you can reach at During the course I'll be giving full instructions on how to use EZ Web

Assignments & Exams


Assignments will be given out every other Friday, collected on the following Friday, and then returned on the Friday after that (see the syllabus & schedule below for full details). For the most part, problems will be taken from Carroll & Ostlie, although some additional questions will be posed from time to time. Unless a valid excuse is provided, late assignments will have a small number of points deducted. Students are encouraged to work together on solving homework problems; however, the final write-up of the problem must be the student's own work, in their own words. The assignments, as they are released, can be downloaded from this list:

Mid-Term Exam

There will be a 50-minute mid-term exam (exam; [File:midterm-solutions.pdf|solutions]]), to be held during the class on Fri Oct 17. This exam will test the material from the first half of the course (mostly, components 1 & 2 described above, and will be open book.

Final Exam

There will be a 2-hour final exam (exam; solutions), to be held 07:45 am – 09:45 am on Sat Dec 20. This exam will test all of the material from the course, and will be open book.


The final grade for the class will depend primarily on weekly assignments (50%); on the mid-term exam (25%); and on the final examination (25%). However, strong and enthusiastic participation in classroom discussions will also be recognized.

Syllabus & Schedule

See the PDF version of this document for the full syllabus & schedule.


  • Drawing an ellipse (XviD)
  • Parameters of an ellipse (XviD)
  • Orbits of the inner planets (XviD)
  • Kepler's second law (XviD)

NOTE: for a discussion on how to play these movies, see the movie help page.


Updated 2009-10-14 03:57:58