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. Pregnant Student Accommodations
  19. Religious Observances
  20. 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

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

No description found

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 goals 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 public class webpage or the class page on blackboard.

Outline of Topics

  1. Hydrostatics and thermodynamics of self-gravitating objects

    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

  2. Star formation

    1. Gravitational collapse of molecular clouds, Jeans mass

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

  3. Life on the main sequence

    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

  4. Life after the main sequence

    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

  5. Colapsed star: structure and emission in isolation

    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, observed stellar properties


Stellar structure equations, Stars in the galaxy


Hydrostatic balance


MESA getting started day



Thermodynamics of a (quasi-)hydrostatic star


Heat transport


Polytropes, Eddington Standard Model




Convective stability/instability


Heat transport by convection

Part 2: Star formation


Star formation, protostars


Energy and 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, Lithium burning


pp and CNO cycles


CNO burning stars


Upper and lower main sequence (CNO and core convection)


Surface T and Saha equation for ionization


Stellar spectra


Core hydrogen burning evolution


Hydrogen depletion, the S-C threshold for the helium core


after helium core formation, helium ignition

Part 4: Life after the main sequence


Red Giants


How to burn helium


-- (fall break)


Helium core flash, beginning of the end for <6Msun



Asymptotic giants and thermal pulses


white dwarf masses, start advance burning stages (MESA project topics due)


MESA workdays


Advanced burning stages


Inert core formation, Chandrasekhar mass


Core collapse


Supernova explosive nucleosynthesis

Part 5: Collapsed stars


White dwarf cooling


-- (thanksgiving holiday)


MESA project workshop


White dwarf interior, crystallization



Neutron stars


MESA project presentations


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

45% homework, 30% 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 Academic Misconduct Policy 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.

Pregnant Student Accommodations

Title IX protects against discrimination related to pregnancy or parental status. If you are pregnant and will need accommodations for this class, please review the University’s FAQs on the UAct website.

Religious Observances

Under the Guidelines for Religious Holiday Observances, students should notify the instructor in writing or via email during the first two weeks of the semester of their intention to be absent from class for religious observance. The instructor will work to provide reasonable opportunity to complete academic responsibilities as long as that does not interfere with the academic integrity of the course. See full guidelines at Religious Holiday Observances Guidelines.

UAct Statement

The University of Alabama is committed to an ethical, inclusive community defined by respect and civility.  The UAct website (www.ua.edu/uact)  provides extensive information on how to report or obtain assistance with a variety of issues, including issues related to dating violence, domestic violence, stalking, sexual assault, sexual violence or other Title IX violations, illegal discrimination, harassment, hate or bias incidents, child abuse or neglect, hazing, threat assessment, retaliation, and ethical violations or fraud.