HST image of the M16 nebula: pillars of creation

Physics 342
Principles of Astrophysics
Spring 2017

Tuesdays and Thursdays
3:20 to 4:40pm
ARC 105, Busch campus
Instructor: Saurabh W Jha


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. 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 Rutgers Prof. Chuck Keeton. (It was written specifically for this course.) Optional, supplementary information can be found in An Introduction to Modern Astrophysics (2nd edition) by Bradley W. Carroll and Dale A. Ostlie (affectionately known as the Big Orange Book).

You will need an iClicker remote for use during class. Please register your clicker by going to the "My Workspace" tab on Sakai and choose the i>clicker tool on the left sidebar to enter your Remote ID. If you have already done this for another class, you should be all set. You may also use the REEF Polling app instead of an iClicker.

Contact Information

Prof. Saurabh W. Jha
Room 315, Serin Physics Building (across Allison Road from the classroom), Busch campus
Email: saurabh[at]physics.rutgers.edu
Phone: 848-445-8962 (email preferred)

Office hours: Wednesdays 3-4pm, or by appointment


Grading will be based on biweekly problem sets (50%), two in-class conceptual midterms (10% each), iClicker conceptual question scores (10%), and the final exam (20%). A final grade of 90% or higher will guarantee you an A.

Problem sets will be posted to Sakai. There will be 6 problem sets during the semester, due roughly every other Thursday at the beginning of class. Problem sets can also be turned in as PDF files via Sakai. It is your responsibility to meet the deadline! No late assignments will be accepted. No exceptions. I will drop your lowest problem set score in calculating your final grade. While that means you could skip a problem set and still get a perfect score, experience has shown it is much better for your grade to turn in all six and have the lowest score dropped.

You are encouraged to work in groups on the problem sets, 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 class notes I post or the textbook). You may not refer to notes, assignments, or solutions, from previous years of Physics 341 or 342 or solutions of the textbook problems.

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.

The final exam will be scheduled by the university: Friday May 5th from 1-3pm in our usual classroom, ARC 105.

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 17,19
dimensional analysis; electron gas
Chapter 1
Jan 24,26
the air we breathe
kinetic theory of gases;
planetary atmospheres;
hydrostatic equilibrium
Ch. 12.1/12.2/12.3
CO 8.1/10.2/10.1
Jan 31, Feb 2
hot in here
blackbody radiation;
planet temperatures
Ch. 13.1/13.2
CO 3.4-5
PS #1 due Feb 2
Feb 7
atmospheric heating
Ch. 13.3/13.4
CO 9.2/20.2
Feb 9   class cancelled due to snow    
Feb 14
interaction of light and matter;
greenhouse effect
Ch. 13.3/13.4
CO 9.2/20.2
Feb 16
star light, star bright
stellar atmospheres
Ch. 14.1/14.2
CO 8
PS #2 due Feb 16
Feb 21
first in-class midterm
in-class midterm
Feb 21
Feb 23
stellar atmospheres; HR diagram
Ch. 15
CO 10.3
Feb 28, Mar 2
nuclear fusion: energetics, reaction rates;
nuclear reactions in stars
Ch. 15
CO 10.3
PS #3 due Mar 2
Mar 7,9
energy transport;
stellar structure
Ch. 16.1/16.2
CO 9.3/10.4-6/11.1
Mar 14,16
Mar 21,23
we are star dust
stellar evolution: low-mass stars;
stellar evolution: high-mass stars
Ch. 16.3/16.4
CO 13/15.1-3
PS #4 due Mar 23
Mar 28,30
white dwarfs; neutron stars
Ch. 17
CO 4.4/16
Apr 4
second in-class midterm;
in-class midterm
Apr 4
Apr 6,11 surveying the Universe
stellar pulsation; Cepheids;
supernovae; cosmic acceleration; dark energy
Ch. 11
CO 29.1/29.3-4
Apr 13,18
cooling; star and galaxy formation
Ch. 8.1.3/19.1/19.2
CO 12.2/2.4/26.2
PS #5 due Apr 13
Apr 20
stars, disks, and planets
Ch. 19.3/19.4
CO 18.2/23.2
Apr 25,27
cosmic microwave background;
Big Bang nucleosynthesis
Ch. 20.1/20.2
CO 29.2
PS #6 due Apr 27
May 5
final exam 1-3pm


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Last updated: April 11, 2017 swj