Physics 341, Fall 2019

Course Information:

Prof. Matthew Buckley (office: Serin W329,

Lectures: Tuesdays/Thursdays 3:20-4:40, ARC 105 (Busch)

Office Hours: Wednesdays 3:00-4:00 and TBA (Serin W329)

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.) In addition, you may find reading in An Introduction to Modern Astrophysics by Carroll and Ostlie helpful, though this book is not required and you should not feel obligated to purchase it. That said, Carroll and Ostlie is a standard reference in astrophysics, so if you are thinking of pursuing a career in this field, you will likely find this book useful in the future.

The Canvas website for the class is here, where enrolled students can find and submit homework.


  • Grading will be based on weekly problem sets (35%), two in-class midterms (15% each), a final exam (20%), and iClicker scores (15%).

  • Weekly homework will be assigned on Thursday in class and due on the following Thursday in class.

  • Collaboration with other students is strongly encouraged, but your write-up of the solutions must be your own. You must write down the names of your collaborators on your write-up. 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.

  • 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.

Student Accommodations

If you require special accommodation in the course, please speak with me as early in the semester as possible. Visit this link for information on Rutgers policies.

Course Schedule

(subject to change)

General concept
Sept 3, 5 Introduction gravity; estimation; dimensional analysis Ch. 1, Sections 1.1 & 1.2  
Sept 10, 12 1-body problem Newton's laws of motion and gravitation;
conservation laws
Ch. 2;
CO 1.1,1.2,2.1,2.2
PS1 due
Sept 17, 19   deriving Kepler's laws; the Galactic center Ch. 3;
CO 2.3,6.1,24.4
PS2 due
Sept 24, 26   Doppler effect; supermassive black holes Ch. 3, Sections 3.2 and 3.3 PS3 due
Oct 1, 3 begin 2-body problem 2-body theory; binary stars Ch. 4, Sections 4.1 & 4.2; CO 2.3,5.4,8.1,7.1,7.2,7.3 PS4 due
Oct 8, 10   binary stars cont'd; midterm exam Ch. 4.3; CO 7.5 Thurs in-class midterm
Oct 15, 17   extrasolar planets; tidal forces Ch. 5; CO 19.2 PS5 due
Oct 22, 24 N-body problems and galaxies basic properties of galaxies; spiral galaxy rotation curves Ch. 7.1 - 7.3; CO 25.1,25.2,24.1,24.2 PS6 due
Oct 29, Oct 31   dark matter; virial theorem Ch. 7.3 - 7.4;
CO 24.3
PS7 due
Nov 5, 7 gravitational lensing elliptical galaxies
lensing principles
Ch.8, Ch. 9.1 - 9.2; CO 2.4,25.4,28.4 PS8 due
Nov 12, 14   lensing principles; microlensing Ch.8, Ch. 9.1 - 9.2; CO 2.4,25.4,28.4 Thurs in-class midterm
Nov 19, 21   galaxy and cluster lensing Ch. 9.3, 10.1-10.2
CO Ch.4
Thursday Thanksgiving
Nov 26, 28 relativistic cosmology the expanding Universe; the accelerating Universe Ch. 11; CO 27.1,
PS9 due
Dec 3, 5   general relativity; applications of general relativity Ch. 10.3 - 10.5;
CO 17.1,17.2
PS10 due
Dec 10   black holes Ch. 10.6, Ch. 11;
CO 17.3
final exam