Department of Astronomy


Faculty Office Hours



Graduate Students

Administrative Resources

Mentoring Resources

Weekly Seminars


Peridier Library

Public Outreach

Graduate Program

Prospective Graduate Student Information

Current Graduate Students

Graduate Awards

Undergraduate Program

Degree & Course Information

Awards, Scholarships & Financial Aid

Research & Career Opportunities

Board of Visitors

College of Natural Sciences


University Course Schedule

Contact Us



MWF 11:00-12:00 · RLM 15.216B · Unique No. 48580


Don Winget

RLM 16.236 · (512) 471-3404 · email

Courses - Spr '09

<  1  2  >

--Printable syllabus (pdf)


Böhm-Vitense, Introduction to Stellar Astrophysics: Volume 2, Stellar Atmospheres
Mihalas, Stellar Atmospheres
Gray, Observations and Analysis of Stellar Photospheres
Rybicki and Lightman, Radiative Processes in Astrophysics


  1. Summary of Observational Data: Motivations for studying stars. Spectral and luminosity classification. Relation of theory and observation.

  2. Elements of Radiative Transfer Theory: Definitions. Emission, absorption, and scattering. Equation of transfer, radiative equilibrium.

  3. Gray Atmospheres: Milne's equation. Two-stream and Eddington approximations. Emergent flux and limb darkening.

  4. Local Thermodynamic equilibrium (LTE): Elements of statistical mechanics. Perfect gases and the Saha equation. Conditions for LTE. Depression of the adiabatic gradient in a partial ionization zone.

  5. Non-LTE: Rate: Rate equations. Radiative and collisional rates; departure coefficients. Calculation of Einstein coefficients and collision cross-sections.

  6. Continuum Opacity: Opacity sources in high-, intermediate-, and low-temperature stellar atmospheres.

  7. LTE Continuum model Atmospheres: Basic equations. Numerical solution of transfer equation: (-iteration; Kurucz's and Feautrier's methods. Temperature-correction procedures.

  8. Results and Comparison With Observations: Absolute energy distributions. The Balmer jump. Sample model atmosphere calculation. Flux distributions for sample model stars. Effect of absorption edges on atmospheric structure, line-blanketing, molecule formation.

  9. Mixing Length Theory: Convection and partial ionization zones. Simple phenomenological models.

  10. Line Spectra: Line absorption profiles. Natural broadening and the Lorentz profile. Doppler broadening and the Voigt profile. Collisional broadening. Stark broadening, Inglis Teller formula.

  11. Line Transfer Problem.: Line transfer equation: pure scattering lines and pure absorption lines. Center-to-limb variations. Schuster mechanisms. Curve of growth and abundance determinations. Model atmosphere line calculations. Line blanketing theory, LTE line formation.

  12. Moving Atmospheres: Modeling stellar atmospheres with winds require hydrodynamic NLTE treatment. Development of a first-principles approach to the problem. Applications to Hot stars.

<  1  2  >