ASTRONOMY 630 - Stellar Atmospheres and Interiors

Spring Semester 2008

Instructor: Eric Sandquist

Office: Physics (P) Building Room 243

Office Phone: (619) 594-2694

Email: erics@mintaka.sdsu.edu

Office Hours: T 9-11 AM, W 3:30-5:30 PM; or by appointment

Prerequisites: none

Lectures: MW at 2:00-3:15 PM in Physical Sciences (PS) 256

Textbook: Stellar Interiors (Hansen, Kawaler, & Trimble)

Optional: The Observation and Analysis of Stellar Photospheres (Gray)

Midterm Exam: the week of March 10, 2008.

Student Oral Presentations: Week of May 5, 2008

Final Exam: Monday, May 12, 2008 at 1:00 PM in PS 256.

Goals:

During this semester I would like to give you practice in several skills that will be helpful for your future:

a good working understanding of stars and the physics that makes them work. Stars demonstrate physical principles covering a huge range - from interactions between elementary particles to oscillations that can affect an entire star. Stars are also the probes we use to understand larger structures in the Universe.
an ability to understand a physical situation using simple calculations. This is a very important skill in deciding where to put your research time to get the most return, but in a practical sense, it is also important for the physics GRE test. By understanding timescale and order-of-magnitude arguments and being able to use simplified models, you should be able to apply your knowledge to determine what is most important in problems you study.
an ability to interpret scientific results and communicate them in a clear manner. A good physical understanding is NOT simply being able to do problems - it also involves being able to see the reasons behind why things happen, and how that can be used to predict the outcome of new situations.

Grading Policy

IMPORTANT NOTE: Because graduate classes are usually small, grading often can't be done in the same way as in undergraduate classes (ensuring that the class average is set at a certain grade). In this class, your performance will be judged against the average for previous ASTR 630 classes. Generally the best students will receive A grades, BUT it is not guaranteed - if your performance in some parts of the course is deficient, it might be possible to get miss an A grade even if you are top in the class. The course grade will be based on

Midterm Exam (20% of grade)
Final Exam (25%)
Oral Presentation and Written Report (20%)
Homework Assignments (35%)

The homework assignments will be generally be composed of problems that ask you to do calculations to give you more familiarity with important topics covered in class; back-of-the-envelope type problems that will ask you to simply model unfamiliar situations; short essays asking you to CLEARLY explain the physics involved in some aspect of stars; and short programming assignments that will build your computational skills. IMPORTANT NOTE: it is OK to work together on homework assignments, but you MUST write your solutions in a way that makes it clear you have thought about things yourself.

The midterm and final exams will mostly be composed of short answer and essay questions that will test your physical understanding of the material, and there will be a small number of problems like the more involved ones from the homework assignments. Both exams will be closed-book. The midterm exam will be given in class, while the final exam will be given during finals week.

Oral Presentation and Written Report

In the last few weeks of the course, you will be asked to choose an article relating to stars from a refereed astronomical journal and give an oral presentation reporting the results. The article must have been published within the last three years. The presentations will be roughly in the style of an American Astronomical Society (AAS) conference oral session. You will have 10 uninterrupted minutes to give your report, followed by up to 5 minutes of questions. As with conference presentations, the time limit will be strictly enforced. The presentations will be graded primarily on demonstrating the importance of the research work, and clarity of presentation.

You will also be asked to write a summary paper (up to 10 pages single spaced) about the article, with more emphasis placed on your understanding of the background material and your evaluation of the limitations of the scientific study. More details will be provided later in the semester.

Reference Book List

Some of the books below (marked with a "*") are on 2-hour reserve at the University Library. You should definitely look at some of these during the semester to supplement the book and the class notes.

Bahcall, J. N. Neutrino Astrophysics (good discussions of nuclear reactions, neutrinos, and standard solar models)
*Bohm-Vitense, E. Introduction to Stellar Astrophysics (v.1: basic stellar observations and data; v.2: stellar atmospheres; v.3: stellar structure and evolution - low-level books)
Bowers, R. & Deeming, T. Astrophysics I: Stars (a good low-to-medium level textbook, but with lots of scattered errors)
*Clayton, D. D. Principles of Stellar Evolution and Nucleosynthesis (probably THE classic book with generally good explanations, but weak on evolution)
Cox, J. P. & Giuli, R. T.Principles of Stellar Structure (2 volumes - probably the best high level textbook, although it is somewhat old and out of print)
de Loore, C. W. H. & Doom, C.Structure and Evolution of Single and Binary Stars (a good medium-level textbook)
*Kippenhahn, R. & Weigert, A. Stellar Structure and Evolution (a good medium-level textbook)
Mihalas, D. Stellar Atmospheres (a high-level textbook)
Prialnik, D. An Introduction to the Theory of Stellar Structure and Evolution (a low-level textbook)
Schatzman, E. L. & Praderie, F. The Stars (a good high-level textbook)
Shapiro, S. L. & Teukolsky, S. A.Black Holes, White Dwarfs, and Neutron Stars (an excellent book on compact stars)

Course Outline

Please keep in mind that the schedule of topics is tentative and subject to change. The rough amount of time devoted to each topic is also included.

Basic Stellar Properties (2 weeks)
- Overview of Observations: The Sun
- Stellar Spectra and Colors
The Stellar Structure Equations (4 weeks)
- mass continuity
- equation of motion
- conservation of energy
  - The Virial Theorem
- second law of thermodynamics
  - radiation energy transport
    - the radiative transport equation
  - convection energy transport
- composition equations
Timescales, Homology, and Simple Stellar Models
The Constitutive Relations (4 weeks)
- equation of state
  - the pressure integral
  - degeneracy
- opacity
- nuclear reaction rates
  - basic reaction rate calculations
  - major energy producing reactions
Methods of Computing Stellar Structure
Stellar Evolution (3 weeks)
- star formation and pre-main sequence
- main sequence
- The Evolution of 1, 5, and 20 Solar Mass Stars
Stellar Atmospheres (2 weeks)
- simple atmosphere models
- formation of spectral lines