Printable syllabus (pdf)
Astronomy 352K: STELLAR ASTRONOMY
Fall 2012 - Unique Number 47785
MWF 11-12, in RLM 15.216B
Chris Sneden, RLM 17.206
Office Phone: (512) 471-1349
Home Phone: 434-0004
office hours: TTh 2:15-3:15
Rodolfo Santana, RLM 16.318
Office Phone: (512) 471-3466
office hours: T 9-10, Th 2-3, or by appt
An Introduction to Stellar Astrophysics
author: Francis LeBlanc
2010, Wiley, paperback edition
Homework Sets: 60% of grade
Hour tests (3 of them): 40%
Final Exam: 0%
Tentative Hour Test Dates:
#1: Friday, September 28, in class
#2: Friday, October 25, in class
#3: Wednesday, Dec 12, 2-5 (final exam slot)
Students with special needs may request appropriate
accommodation; call UT's office of Services for
Students with Disabilities, 471-6259.
Companion 152M Lab:
Not required, but a good idea for practical training
Subject Matter, Goals, and Miscellaneous Comments
What is it? To whom am I speaking?
Astronomy 352K is a junior/senior-level
introduction to stellar astronomy and astrophysics, with emphasis on observational and
empirical methods for studying stars via the light they emit. It is designed with upper-division
astronomy majors in mind, but it is also suitable for students majoring in closely
related fields such as physics, mathematics, or engineering. See an additional remark in the
textbook paragraph below.
Prerequisites? I expect you to have taken Physics 316 (Electricity & Magnetism) and its
associated lab course Physics 116L, which have as their prerequisites Physics 301 (Mechanics)
and 101L, and relevant math courses. It is acceptable to have taken instead the Engineering
Physics courses 303K and 303L, with their lab courses. Astronomy draws on such a wide
variety of areas in physics that we cannot expect you to have prior preparation in all of them,
and so we will introduce physical ideas and laws as needed. (Examples include the theory of
radiation, atomic structure, and statistical mechanics.) We will be most interested
in applying physical principles, rather than in deep and lengthy derivations. In general
the mathematical manipulations expected of you (e.g., on homework sets) will be pretty
Background? We do not assume that you have strong (indeed, any!) previous
background in astronomy, although many of the students already will have taken other upper-division
astronomy courses or at least had an introductory astronomy course such as AST 307
or 301 (but see the new UT restrictions on counting such ”0” courses). If you find that there
are gaps in your basic astronomical knowledge, please ask me or the TA to explain or
elaborate (either in class or during office hours). You might also find it helpful to consult one
of the many fine introductory textbooks that are widely available (I can lend you one of
them). It should take you only a few evenings to master all of the relevant material that is
contained in these books.
Overlap with other courses? There is a small amount of overlap between AST 352K
and AST 358 (Galaxies and the Universe), AST 353 (Astrophysics), and AST 352L (Positional,
Kinematical, and Dynamical Astronomy). We will try to avoid excessive redundancy,
but that is inevitable in some subject areas, since not all members of the present class will
have taken these other courses. I intend at least part of AST 352K to lead pretty directly
into AST 353.
Textbook? We will be using Francis LeBlanc’s An Introduction to Stellar Astrophysics.
This book is fairly new. IT covers material appropriate to both this course and AST 353
(the parts that include discussion of stellar interiors and nuclear energy generation). This is
a nice single source for basic information about stars, and I like its presumption that many
readers will have had no prior introduction to astronomy in any detail.
Class notes? I also am posting copies of my notes on the class web site. I have alternated
teaching this course with Prof. Harriet Dinerstein, and between us we have pretty much
settled on the topics and presentation order that we like. Harriet made a major upgrade
in the class notes a few years ago, and the current version has a lot of her ideas in it. You
will easily notice that my presentations will alternate between working through these notes
and trying to resonate with the textbook. There are sections of the course that will be “all
book”, or “all notes”, or a mixture.
My bias in this course? I regard AST 352K as a vital link between the basic, often
elegant physics and mathematics that you have ingested at UT for the past two-three years,
and the real, often messy world of astronomical research. Astrophysics combines elements
from all areas of physics to offer coherent theoretical models for how the solar system, galaxy,
and universe are constructed and how they have and will evolve. If you are looking for that
in this course, forget it. Theoretical astrophysics cannot really derive rational models for
an object without appealing to observational astronomy. I am not an astrophysicist as the
term is sometimes meant (that is, I am not a theorist). I am an observational astronomer,
and proud of it. And observational astronomy is what you will find covered in this course.
Not how is the universe constructed, but how does one practically assemble the basic data
about particular astronomical objects (stars) that can be gainfully used in constructing the
story of the universe?
So forget cookbook problems? Not entirely, but we will deal as much as possible
with real data from the literature that have been obtained at various astronomical facilities
over the past decades, and which now are readily available for study. Many of the homework
problems will encourage you to seek data from basic astronomical catalogs. These sources
can be found on appropriate web sites.
Homework, and your approach to it? The homework sets are the keys to what I want
to get done in this course. I intend to be deliberately vague in some of the assignments. I
admit that this is a sometimes maddening ploy. Real astronomical research usually does not
admit cookbook solutions to interesting problems, and I want you to get used to that. Such
an approach is also a signal on my part that I encourage interactions with you outside class.
Feel free to discuss with me the course material, problem sets, or any other astronomical
topic that come to mind. On the first page I give the formal office hours, but you of course
may set up appointments with me at other rational times of day. Notice also that I give
my work number, email address, and my home phone number. I greatly prefer contact in
person or a phone call; emails to me can get deeply buried. I would not give out my home
phone number if I did not expect calls in the evening whenever you need to. (It is true that
we are the only Snedens in the Austin telephone directory.) I want to help you do well in
this course, but I need you to make contact! Don’t be shy: remember that the truly stupid
question is the unasked one.
Caveat Emptor! Two warnings must be given, one applicable to all faculty members
here and one specific to me. First, in this department you deal with professional astronomers.
The good part is that you get very close to current research, and that can be very exciting.
The bad part is that we tend to travel a lot (most obviously to observatories in remote and
exotic locales), and probably I will need to excuse myself from class a couple of times during
the semester. At present I have a McDonald Observatory run for which I must leave on
Thursday afternoon October 25, and return late Friday November 2. This means that I will
miss class on October 25, 29, 31, and November 2. A substitute lecturer will pinch-hit for me
in class on those occasions. I also plan to have the second hour exam on one of those days.
Simply put, all class meetings will occur as scheduled. Second, I am currently Letters Editor
of The Astrophysical Journal. This means that inevitably I am pulled in many different
teaching/service/research directions simultaneously, and frankly I am very busy. However,
this should not become your problem! I expect you to work in this class, and you should
expect no less of me. Do not feel the slightest hesitation in pushing me to make time for you
outside of class; politely in the beginning, but more firmly if I do not respond well. Your
interaction in this course can only aid your understanding.
Finally, a Carrot Instead of a Stick: In spring 2012 I will be offering a guided research
position to an interested student who has successfully (A-B grade) completed AST 352K this
semester. Usually the student will sign up for some course number that signifies independent
study. Real investigation into the chemical composition of stars will occur! Some background
buildup will be necessary, but then collaborative research can commence. A grade for that
course will be the least interesting outcome, as successful work (often going beyond the spring
semester) should lead to a published paper and/or attendance at a professional meeting. A
list of past undergrad research assistants and their projects will be shown to you at the start
of the semester.
Preliminary Course Outline (subject to revision)
- Introduction and Vital Observational Statistics of Stars: positions, distances, magnitudes,
- The Basic Quantities of Radiation: intensity, flux, blackbodies
- Interpreting Stellar Magnitudes: luminosity & effective temperature; stellar photometry
& color indices; effects of the Earth's atmosphere
- The Heart of Observational Stellar Physics: spectroscopy; stellar spectral types; excitation
& ionization equilibria; the Hertzsprung-Russell diagram
- Further Extractions from Spectroscopy: radial velocity & proper motion; interstellar
extinction; binary stars & the measurement of stellar masses; the Mass-Luminosity
- Variable Stars: Cepheids, RR Lyraes, Long-Period Variables; white dwarf pulsators;
close binary systems (mass-exchange & contact binaries; cataclysmic variables; novae;
- Star Clusters: young clusters/pre-MS evolution; Main Sequence turnoffs & cluster ages;
globular clusters; etc.
- Stellar Atmospheres: radiative transfer; basic principles of model atmospheres; spectral
lines & abundance determinations.
- (as time permits:) Unique (mostly spectroscopic) stellar types: peculiar-A stars; Be
stars; low metallicity stars; etc.