ASTR 5700: Stellar Interiors
APS, University of Colorado

Image at left: Latest extreme ultraviolet image of the Sun


The aim of this course, in brief, is to cover the essential physics of the internal structure of stars, including the basic equations of stellar structure and the microphysics of the equation of state, opacity, and nuclear reactions. Semi-quantitatively, we will examine how stars evolve prior and subsequent to the main sequence. Observations will be introduced to motivate what we're doing, and to introduce essential terminology, but we will not deal with the physics of stellar atmospheres.


Lectures will be at 2:00 pm Monday / Wednesday / Friday in room G1B27. My office is A909 (in the JILA tower) - feel free to stop by anytime with queries / problems / suggestions. The highest probability of finding me in the office is in the afternoon / early evening. Grading will be based on weekly problem sets (total 60%) plus participation in 3 in class discussion sessions (15%). A paper or project on a contemporary topic in stellar astrophysics of your choice will make up the remaining 25% (see guidelines and suggestions). There will be no exams. Lecture notes and problem sets will be posted here as the course progresses.


Lecture 1: Overview of the problem of stellar structure
Lecture 2: Astronomical nomenclature and stellar classification
Lecture 3: Virial theorem, 47 Tuc color-magnitude plot
Lecture 4: Timescales
Lecture 5: Structure equations
Lecture 6: Equation of state
Lecture 7: Saha equation
Lecture 8: Nuclear matter
Lecture 9: Ideal gas plus radiation
Lecture 10: Partial ionization
Lecture 11: Polytropes
Lecture 12: Polytropes and the Chandrasekhar mass
Type 1a Supernovae (link to Hillebrandt & Niemeyer's review for further information)
Lecture 14: Radiative transfer preliminaries
Lecture 15: Radiative diffusion
Lecture 16: Opacity sources
Lecture 17: Convective stability
Lecture 18: Mixing length theory
Lecture 19: Stellar energy sources
Lecture 20: Nuclear reaction rates
Lecture 21: Hydrogen burning reactions
Lecture 22: White dwarf cooling: Paper on white dwarf cooling
Lecture 23: Helium burning
Lecture 24: Boundary conditions
Lecture 25: Rotation
Lecture 26: Brown dwarfs
Lecture 27: Hayashi tracks
Lecture 28: Star formation: see also movies by Matthew Bate
Lecture 29: Stellar birthline
Lecture 30: Pre-main-sequence stellar rotation
Lecture 31: The main sequence: homology
Lecture 32: The main sequence: chemical evolution
Lecture 33: Post-main-sequence evolution
Lecture 34: More post-main-sequence evolution
Lecture 35: Type II SN: see also Adam Burrow's movies
Lecture 36: Binary evolution: Roche approximation
Lecture 37: Wind-fed accretion
Lecture 38: Common envelope evolution
Lecture 39: Disk accretion in binaries


Helioseismology experiments: SOHO / MDI
Zero metallicity stars..., J. Tumlinson & J.M. Shull (2000)
Astrophysics preprints: astro-ph (for the hopelessly addicted new papers appear at 6pm Colorado time)


The recommended textbook for the course is Stellar Interiors by C.J. Hansen and S.D. Kawaler. There are many other good and / or classic texts, e.g. Stellar Structure and Evolution by R. Kippenhahn and A. Weigert, and Principles of Stellar Evolution and Nucleosynthesis by D.D. Clayton. Both of these should be on reserve in the library. The second volume of Theoretical Astrophysics by T. Padmanabhan (which may be useful for other courses) also has some discussion of stellar structure and evolution.

Phil Armitage (email: pja at

Office: A909 JILA (in the JILA tower)
Tel: 303-492-7836