1. Contact Information
  2. Prerequisites
  3. Course Description and Credit Hours
  4. Required Texts
  5. Course Objectives
  6. Student Learning Outcomes
  7. Other Course Materials
  8. Outline Of Topics
  9. Exams and Assignments
  10. Grading Policy
  11. Policy on Missed Exams and Coursework
  12. Attendance Policy
  13. Notification of Changes
  14. Custom Sections
  15. Statements on Academic Misconduct
  16. Statement On Disability Accommodations
  17. Severe Weather Protocol
  18. UAct Statement

Stars & Stellar Evolution

AY 450-001Fall 2017 | 3 Credit Hours


Dr. Dean Townsley

Contact Information

UA Campus Directory:


UA Course Catalog Prerequisites:

MATH 238

While there is currently no formally listed undergraduate prerequisite, preparation at the equivalent of MATH 238, Applied Differential Equations 1, is expected for undergraduates. It would also help undergraduates to have taken at least AY 101, Introductory Astronomy for non-science majors, or, preferably, AY 204 and 206, Introductory Astronomy for science majors. For graduate students, no prior astronomy courses are expected.

Course Description

Course Description and Credit Hours

This course is intended to facilitate a fairly complete understanding of stars, including their structure, evolution (formation, stages of burning, end states), synthesis of elements, and the physical processes involved in each of these, as well as introduce the modern computational modeling techniques used to apply stellar physics to stars. For astronomy students, this course will provide the background necessary to understand the underlying principles of stellar processes and modelling as they are used both in ongoing research into stellar physics and phenomena and in support of other areas of astronomical research where stellar populations, products and processes are important. In a broader context, relevant for any physics student, this course will discuss how understanding the physical principles in fluid dynamics, high-density materials, heat transfer, plasma physics, nuclear structure, and nuclear processes are assembled into our modern understanding of how stellar objects behave, and how the study of stars pushes the frontier of understanding in these areas of physics.

Lecture Meeting: Monday, Wednesday, and Friday 12:00-12:50 in 328 Gallalee Hall.

Required Texts

Required Texts from UA Supply Store:

Texts:Stellar Interiors by Hansen, Kawaler, and Trimble; Principles of Stellar Evolution and Nucleosynthesis by Clayton
Supplementary text: Galactic Astronomy by Binney and Merrifield

A note on texts: Most material will be drawn from Hansen, Kawaler, & Trimble, which is quite readable.  Some topics requiring more detail on nuclear processes will be drawn from Clayton.  Binney and Merrifield is a suggested reference text for general astronomical background, conventions, and arcana. Other upper-level general astronomy texts can fill a similar role.

Student Learning Outcomes

Course goal phrased as learning outcomes:

At the conclusion of this course, all students will be able to

  • describe the interior structure, appearance, and activity of stellar objects from formation to remnant, and how it depends on the star's mass.
  • demonstrate understanding of the macrophysical or microphysical process that governs the transitions of stars from one stage of their life cycle to the next, and dominates their behavior during each stage.
  • demonstrate in what way many gross stellar properties arise from simple scaling relations, how such relations can capture basic physical understanding, and be able to apply scaling relations to triage and assess new astrophysical problems.
  • discuss and draw conclusions about how the physics-based components (e.g. microphysical material properties; measured and calculated nuclear interactions) of modern numerical models of stars, stellar processes or stellar populations can influence the outcome of calculations for both individual stars and stellar populations, clusters and galaxies, and their products.

In addition, graduate students will be able to

  • understand the context of ongoing research in stars, stellar populations and stellar physics, at a level that enables comprehension of the content and scope of research literature which is not exclusively specialist (reviews, ApJ letters, proposals, topical sessions at national meetings, well-written topical articles).
  • identify the areas of ongoing research into stellar processes and the physics which is important for stellar properties and products, characterize the unanswered questions, and integrate future developments in these areas into their understanding of stars.

Other Course Materials

Students are expected to have access to a unix computing environment of some form.  Mac OS X, Linux, or others are all sufficient.  Students should consult with the instructor if they need assistance with this, as some university facilities are available, though typically a student's personal computer is most convenient.

We will be using the Modules for Experiments in Stellar Astrophysics (MESA) available from mesa.sourceforge.net and using some materials available at mesastar.org.

Lecture notes, homeworks and various other resources (figures from class, links to papers, inlists for MESA) will be available through the class webpage.

Outline of Topics

    1. Hydrostatic equilibrium in spherical symmetry, Virial theorem

    2. Equations of state

    3. Simple stellar models and gravitational contraction

    4. Importance of radiation pressure

    5. Diffusion of heat and stellar luminosities

    1. Gravitational collapse of molecular clouds, Jeans mass

    2. Evolution of protostars, fully convective models. The Hayashi track

    1. Thermonuclear energy generation - processes and rates

    2. CNO vs. pp burning, the Solar neutrino problem

    3. Degeneracy and brown dwarf formation

    4. Stellar masses, temperature, radii and lifetimes. IMF

    5. Convection. where and why it occurs

    6. The Saha equation, simple atmospheres, spectroscopy

    1. Degeneracy during stellar evolution. Chandrasekhar limit.

    2. Low mass stars: red giants, mass loss, shell burning

    3. Massive stars: CO burning, Ne photodisintegration, neutrinos

    4. Collapse of Iron cores, core collapse supernovae, nucleosynthesis

    1. White dwarf formation, thermal cooling and observations

    2. Neutron star formation, structure and cooling

Approximate Daily Topic Schedule

Part 1: Hydrostatics and thermodynamics of self-gravitating objects
Course overview, structure equations, stars in galaxy
Hydrostatic balance
MESA, Thermodynamics of a hydrostatic star, heat transport
Eddington Standard Model
Photospheres, starting convection
Heat transport by Convection
Part 2: Star formation
Star formation, protostars, contraction
Contraction, initial mass function, starting nuclear fusion
Nuclear fusion, tunneling
Nuclear fusion for a star, first fusion stages
Part 3: Life on the main sequence
Deuterium main sequence, Lithium, CNO cycle
CNO cycle, CNO burning stars
Upper and lower main sequence, Saha equation
Saha equation for ionization, Stellar spectra
Evolution during main sequence to hydrogen depletion
Hydrogen depletion and after helium core formation
Part 4: Life after the main sequence
Red Giants, how to burn helium
Helium core flash
Completion of evolution for stars below 6 Msun (MESA project topics due)
white dwarf masses, start late burning
-- (fall break)
neutrino losses, carbon burning, late burning stages
Formation of Fe core, Chandrasekhar mass, core collapse
Supernova explosive nucleosynthesis
Part 5: Collapsed stars
White dwarf cooling
MESA project workshop
White dwarf interior, crystallization
Neutron stars
MESA project presentations
Final Exam (time by appointment)

Exams and Assignments

Semi-weekly (approximately every other week) homeworks will be assigned.  Each student is expected to complete the homework individually, though discussion among students is fine.  Each homework will consist of some problems for undergraduates (AY 450), some shared problems for both undergraduate and graduate students, and some problems for graduate students only (AY 550).

Each student will perform a semester project on a topic of their choosing using the MESA stellar evolution code.  Results will be presented in an in-class presentation of about 10 minutes and written up briefly in about 5 pages.  The topic will be chosen by the date indicated in the class schedule, in consultation with the instructor.  Graduate student (AY 550) projects are expected to be broader in scope, for example exploring multiple parameters or more subtle questions, than undergraduate (AY 450) projects.

The final exam will be an individually administered oral exam with the instructor approximately 30 minutes in length.  Undergraduates enrolled in AY 450 will have a lower expectation of performance than graduate students enrolled in AY 550.

Grading Policy

55% semi-weekly homework, 20% project based on MESA stellar evolution code, 25% oral final exam

Policy on Missed Exams and Coursework

All coursework must be completed.  Late work will be accepted with a documented excuse. Generally late work received after solutions are distributed and without appropriate arrangements with the instructor will receive a large penalty.

Attendance Policy

Attendance and participation in all classes is expected (except for circumstances outside of the student's control) despite attendence not forming any part of the formal grade.

Notification of Changes

The instructor will make every effort to follow the guidelines of this syllabus as listed; however, the instructor reserves the right to amend this document as the need arises. In such instances, the instructor will notify students in class and/or via email and will endeavor to provide reasonable time for students to adjust to any changes.

Statement on Academic Misconduct

Students are expected to be familiar with and adhere to the official Code of Academic Conduct provided in the Online Catalog.

Statement On Disability Accommodations

Contact the Office of Disability Services (ODS) as detailed in the Online Catalog.

Severe Weather Protocol

Please see the latest Severe Weather Guidelines in the Online Catalog.

UAct Statement

The UAct website provides an overview of The University's expectations regarding respect and civility.