Physics 341: Principles of Astrophysics
Fall 2014
3:204:40 T Th
Room: ARC 105
Text: Principles of Astrophysics by Charles Keeton
Course Description
Astrophysics is the application of physical principles to astronomical systems. In Physics
341 and 342 you will learn how to use gravity, electromagnetism, and atomic, nuclear, and
gas physics to understand planets, stars, galaxies, dark matter, and the Universe as a whole.
Gravity is the dominant force in many astronomical systems, and it will be our focus in
Physics 341.
Some astrophysical systems are described by equations that are fairly easy to solve, and we
will study them. However, many interesting systems cannot be solved exactly. Nevertheless,
we can often use physical insight and carefully chosen approximations to understand the key
features of a system without sweating the details. One goal of the course is to develop that
skill. As you will see, it will take us very far (through the whole Universe, in fact!).
Another goal is to learn about recent advances in astrophysics, a very dynamic field of
research.
Prerequisites for this class are two semesters of physics and two semesters of calculus. I
will briefly review physical principles as we need them, but it is assumed that you have seen
them before. I will also assume familiarity with vector calculus. Some of the assignments
may involve a bit of computation that can be done with programs like Excel, Google
Spreadsheets, Maple, Matlab, or Mathematica.
The recommended textbook for Physics 341 (and 342) is Principles of Astrophysics: Using
Gravity and Stellar Physics to Explore the Cosmos, by Prof. Chuck Keeton. (It was written
specifically for this course.)
Grading Policies
Grading will be based on weekly problem sets (60%), two inclass midterms (10% each),
and iClicker scores (20%, with a bonus for active class participation).
Weekly problem sets will be posted to Sakai on Thursday afternoons, and will be due the following
Thursday at the beginning of class. Problem sets can also be turned in via our Sakai
website in PDF format.
Collaboration with other students is strongly encouraged, but your writeup of the
solutions must be your own. You must write down the names of your collaborators on your
writeup. You must also cite any external sources you use (other than the textbook).
You may not refer to notes, assignments, or solutions from previous
years of Physics 341 or 342.
Always show your work. You will not receive full credit if you do not show your work. I will never look for a specific answer. Rather, I am always looking for the reasoning behind the answer.
In general, late homework will automatically receive a maximum of half points. Seek arrangement with me at least 24 hours in advance if you think you have a legitimate excuse for late work. After I have graded and handed back homework, I will not accept that homework anymore.
Auditors are welcome. Please let me know if you are interested in auditing the class.
Students with disabilities, please visit this link.
Contact Information
email: abrooks at physics.rutgers.edu
office: 306 Serin
Tentative Schedule
Date

General Concept

Topic(s)

Text

Due

Sept 2, 4

Introduction 
gravity; estimation; dimensional analysis 
Ch. 1,
Sections 1.1 & 1.2


Sept 9, 11

1body problem

Newton's laws of motion and gravitation;
conservation laws

Ch. 2

PS1 due

Sept 16, 18


deriving Kepler's laws; the Galactic center

Ch. 3

PS2 due

Sept 23, 25

begin 2body problem

Doppler effect; supermassive black holes;
2body theory; equivalent 1body problem

Ch. 4, Section 4.1

PS3 due

Sept 30th, Oct 2nd


binary stars; extrasolar planets

Ch. 4, Sections 4.2 & 4.3

PS4 due

Oct 7, 9


transiting planets; tidal forces

Ch. 4, Section 4.3
Ch. 5

PS5 due

Oct 16, 18

3body problem

Lagrange points; asteroids; close binaries;

Ch. 6

Thurs inclass midterm

Oct 21, 23

Nbody problems and galaxies

basic properties of galaxies; spiral galaxy rotation curves;
dark matter; galactic structure beyond rotation

Ch. 7

PS6 due

Oct 28, 30


virial theorem; elliptical galaxies; galaxy interactions

Ch. 8

PS7 due

Nov 4, 6

gravitational lensing

basic principles; microlensing; galaxy and cluster lensing

Ch. 9

PS8 due

Nov 11, 13

relativity

special and general relativity

Ch. 10, Sections 10.1  10.3

PS9 due

Nov 18, 20


applications of general relativity; black holes

Ch. 10, Sections 10.4  10.6

PS10 due

Nov 26

No class all week



Thursday Thanksgiving

Dec 2, 4


expanding Universe; geometry and dynamics;
dark energy; future of the Universe

Ch. 11

PS11 due

Dec 9




in class final exam

