Physics 342
Principles of Astrophysics
Spring 2019

Tuesdays and Thursdays
3:20 to 4:40pm
ARC 105, Busch campus
Instructor: Alyson Brooks


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. In Physics 342 we will focus on the question: How did we get here?

Our story will include the nucleosynthesis of hydrogen and helium in the first few minutes after the Big Bang 13.7 billion years ago, the formation of stars from this primordial gas, and the forging of heavier elements, such as carbon, nitrogen, and oxygen, among all others within these stars' nuclear furnaces. Around at least one star in the Universe some of these heavy elements coagulated to form a rocky planet with a tenuous atmosphere. On this planet Earth, the energy from the star and the gas in the atmosphere were just right to allow the emergence of life. The energy that sustains us originated deep in the Sun, thanks to E=mc2 . The atoms that comprise our bodies were made inside dying stars. Literally, we are star dust. The goal of Physics 342 is to understand the physics of this remarkable story.

Some astrophysical systems are described by equations that are fairly easy to solve, and we will certainly study them. However, many interesting systems cannot be solved exactly. Nevertheless, we can often use physical insight and approximate calculations to understand the salient 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. Previous study of modern physics is a must. I will briefly review physical principles as we need them, but assume 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. Note that Physics 341 is not a prerequisite for Physics 342; the two courses are designed to be complementary, but independent.

Lectures will be based on the course textbook, Principles of Astrophysics: Using Gravity and Stellar Physics to Explore the Cosmos, by Prof. Chuck Keeton. (It was written specifically for this course.)

Contact Information

Prof. Alyson Brooks
Room 306, Serin Physics Building (across Allison Road from the classroom), Busch campus
Email: abrooks[at]
Phone: 848-445-8877

Office Hours: Wed 2-4, or by appointment

Grading Policy

Grading will be based on problem sets (35%), two in-class midterms (15% each), a final exam (20%), and iClicker scores (15%). I will drop your lowest clicker score.

Problem sets will be posted to Sakai. There will be 10 problem sets during the semester, due roughly every Thursday at the beginning of class. Problem sets can also be turned in as PDF files via Sakai.

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.

You are encouraged to work in groups on the problem sets, but your write-up of the solutions (including any plots) 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 use notes, assignments, or solutions from previous years of Physics 341 or 342.

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.

The final exam will occur on Friday, May 10 at 12pm. Location: Pharm 111.

Schedule: Topics and Assignments

This syllabus may be modified as the semester progresses.

Note: Under the "Text" column, "Ch" mark the Chapters in Keeton. "CO" refers to Carroll & Ostlie, on reserve at the Library of Science and Medicine

General concept
Jan 22,24
dimensional analysis;
electron gas
Chapter 1
Jan 29,31
The air we breathe
kinetic theory of gases;
planetary atmospheres;
hydrostatic equilibrium
Ch. 12.1/12.2/12.3
PS #1 due
Feb 5,7
Hot in here
blackbody radiation;
planet temperatures
Ch. 13.1/13.2
PS #2 due
Feb 12,14
atmospheric heating;
greenhouse effect
Ch. 13.3/13.4
PS #3 due
Feb 19,21
Star light, star bright
HR diagram;
nuclear fusion
Ch. 15.1/15.2
PS #4 due
Feb 26,28
first in-class midterm ;
nuclear reactions in stars
Ch. 15.3
Thurs in-class midterm
Mar 5,7
energy transport;
stellar structure
Ch. 16.1/16.2
PS #5 due
Mar 12,14
stellar atmospheres
Ch. 14.1/14.2
CO-chapter 8
PS #6 due
Mar 19,21
Mar 26,28
We are star dust
stellar evolution: low-mass stars;
stellar evolution: high-mass stars
Ch. 16.3/16.4
PS #7 due
Apr 2,4
second in-class midterm;
degeneracy pressure
Ch. 17
Thurs in-class midterm
Apr 9,11
white dwarfs & neutron stars;
Ch. 17
Apr 16,18
star and galaxy formation;
Ch. 8.1.3/19.1/19.2/19.3
PS #8 due
Apr 23,25
stars, disks, and planets;
cosmic microwave background
Ch. 19.4/20.1
PS #9 due
Apr 30, May 2
Big Bang nucleosynthesis;
No class Thurs
Ch. 20.2
PS #10 due
May 10
Final Exam
Pharm 111


Here are some web resources you may find illuminating or indispensable:

Other Items

Students with disabilities should consult the department policy.

Students will be held to the Rutgers policy on academic integrity.

Just In Case Web App
Access helpful mental health information and resources for yourself or a friend in a mental health crisis on your smartphone or tablet and easily contact CAPS or RUPD.

Counseling, ADAP & Psychiatric Services (CAPS)
(848) 932-7884 / 17 Senior Street, New Brunswick, NJ 08901
CAPS is a University mental health support service that includes counseling, alcohol and other drug assistance, and psychiatric services staffed by a team of professional within Rutgers Health services to support students’ efforts to succeed at Rutgers University. CAPS offers a variety of services that include: individual therapy, group therapy and workshops, crisis intervention, referral to specialists in the community and consultation and collaboration with campus partners.

Violence Prevention & Victim Assistance (VPVA)
(848) 932-1181 / 3 Bartlett Street, New Brunswick, NJ 08901
The Office for Violence Prevention and Victim Assistance provides confidential crisis intervention, counseling and advocacy for victims of sexual and relationship violence and stalking to students, staff and faculty. To reach staff during office hours when the university is open or to reach an advocate after hours, call 848-932-1181.

Disability Services
(848) 445-6800 / Lucy Stone Hall, Suite A145, Livingston Campus, 54 Joyce Kilmer Avenue, Piscataway, NJ 08854
The Office of Disability Services works with students with a documented disability to determine the eligibility of reasonable accommodations, facilitates and coordinates those accommodations when applicable, and lastly engages with the Rutgers community at large to provide and connect students to appropriate resources.

Scarlet Listeners
(732) 247-5555
Free and confidential peer counseling and referral hotline, providing a comforting and supportive safe space.

Astrophysics at RutgersDepartment of Physics and AstronomyRutgers University

Last updated: December 12, 2018 by Alyson Brooks