Astronomy 320: Spring 2015

Theoretical Astrophysics

1st galaxies: gas density (Parry, Ricotti & Gnedin 2015) 

Modern astronomy has its roots firmly grounded in the fundamental principles of physics (both classical and quantum). Furthermore, many branches of physics as we know them today trace their origins to the search for universal physical laws to explain natural phenomena discovered and analyzed by astronomers.

The goal of theoretical astrophysics is to provide physical and conceptual understanding of the diverse systems that represent our universe. Introductory astronomy courses are often organized by scale (planets, stars, galaxies and the universe as a whole) and observational astronomy courses are often organized by wavelength because of the different technologies. To emphasize the different approach needed for developing a theoretical framework, this course is organized into themes of governing physical principles. For each of the three main themes (gravity, gas physics and quantum physics), we start with fundamental principles and then discuss applications in various astronomical contexts. We will also discuss systems in which several principles interact synergistically and demonstrate how astrophysical theories are developed by successive model refinements and confrontation with data. We will show how application of simple physical laws can explain the observed properties of an astounding range of astronomical objects!

I will assume a basic knowledge of astronomical concepts (up to the ASTR120/ASTR121 level) as well as basic physics (up to the PHYS270/PHYS271/PHYS273 level)


    Instructor:  		Massimo Ricotti
    Class:       		CSS 0201
    Lectures:    		Tuesday and Thursday from 11:00pm to 12:15pm
    First class: 		Tue Jan 27 
    Last  class: 		Tue May 12 
    TA:		 		Blake Hartley
    Discussion (w/Blake):	Wednesday from 2:00pm to 2:50pm
    First discussion: 		Wed Feb 4th

What's New?

March 3: Guest Lecturer: Doug Hamilton will talk about the Virial theorem and a cool application to Globular Clusters.
Feb 26: Problem Set #3 posted (due March 6th in order to practice for the Midterm: it is a Friday...put it in my mailbox or office).
Feb 26: Snow day ... again (no class)
Feb 19: Problem Set #2 posted (due Feb 26th).
Feb 17: Snow day (no class)
Feb 3: Problem Set #1 posted (due Feb 12).
Jan 28: No discussion session on Wed 28 Jan
Jan 27: First class

Contact info and Notes

Course Outline

The Syllabus is available in PDF format (updated version that fixes a typo on the date of the exams).


GRAVITY (notes)
#1Jan 27 Introduction; Recap of Newton’s laws and the conservation of momentum
#2Jan 29 Newtonian gravity
#3Feb 3 One body problem - conservation laws and constants of motion
#4Feb 5 One body problem - solving the equation of motion
#5Feb 10 One body problem - derivation of Kepler's Laws
#6Feb 12 One body problem - cont.
#7Feb 17 Snow Day (class cancelled)
#8Feb 19 Two-body problems and binary systems (notes)
#9Feb 24 Two + one (restricted three) body problem - Lagrange points and effective potential
#10Feb 26 Snow Day (class cancelled)
#11Mar 03 N-body dynamics - the virial theorem
#12Mar 05 N-body dynamics - two body relaxation
- Mar 10 MIDTERM (in class)
#13Mar 12 Pressure and the concept of hydrostatic equilibrium
#14Mar 24 Atmospheres in an external gravitational field
#15Mar 26 Self-gravitating atmospheres
#16Mar 31 Introduction to thermodynamics and statistical mechanics
#17Apr 02 Statistical mechanics of ideal gas
#18Apr 07 Radiation gases
#19Apr 09 Radiation gases (cont) and applications to Cosmology
#20Apr 14 Brief introduction to hydrodynamics
#21Apr 16 The Bohr model of the atom
#22Apr 21 Particle wave duality and particle in a box
#23Apr 23 Fermions and bosons; Fermi-Dirac and Bose-Einstein statistics
#24Apr 28 Degeneracy pressure and while dwarf
#25Apr 30 Type-1a supernovae and neutron stars
#26May 05 Schrodinger’s approach to Quantum Mechanics
#27May 07 The structure of the hydrogen atom
#28May 12 Review
-May 14 Final exam (in class, Thursday 8:00am-10:00am


There are no required textbooks
Texts Recommended for this course are:
  • Astrophysics for Physicists, by Arnab Rai Choudhuri,
    (Cambridge University Press, 2010) ISBN-13: 978-0521815536
  • Astrophysics in a Nutshell, by Dan Maoz,
    (Princeton University Press, 2007) ISBN-13: 978-0691125848

Course Grading

  • Class participation 10%
  • Homework 30%
  • Midterm exam 25%
  • Final exam 35%
Letter grades will be assigned guided by the following scheme.
  • A 100% - 90%
  • B 89.9% - 80%
  • C 79.9% - 70%
  • D 69.9% - 60%
  • F below 60%
I will also adopt the finer division of the letter grades using pluses and minuses.


Homework will be assigned every week or every other week. Their due dates will be announced at the time they are assigned. On the due date the students will be expected to turn in their homework in class. The homework turned in will be graded and returned to the students. I will provide solutions and discuss them in class.

Problem setDateProblem SetExtras
#1Feb 3Feb 12PDF 
#2Feb 19Feb 26PDF 
#3Feb 28March 6(Friday)PDF 

Wiki pages related to class's discussions

Class #1
Class #2
Discussion Section #7
Class #8
Class #9