TÄHT6009 Theoretical astrophysics 8 ECTS
Organised by
Person in charge
Juri Poutanen
Planned organizing times
Period(s) I II III IV
2016–2017 X X
2017–2018 X X
Preceding studies

Learning outcomes

After the course the student knows basic radiation terms. Student can write the radiative transfer equation and solve it using different approximations. Students can compute the ionization state of matter. Student knows basic methods to compute stellar atmospheres, can compute emission and absorption coefficients and use them in the radiative transfer equation. Student is able to explain what is the Rosseland mean opacity and why it is important. Student is able to explain the meaning of Einstein coefficients and how using them to explain the existence of lasers and masers. Student is aware of the basic mechanisms that widen spectral lines, knows how to use the curve of growth to compute the abundance of elements. Student is able to explain the difference between degenerate and ideal gas. Student is capable of writing the main equation describing stellar structure and knows the main nuclear reactions.


Description of radiation. Black body radiation. Emission and absorption of radiation, source function. Radiative transfer equation and its methods of solution, Eddington approximation, Schuster-Schwarzschild method, Chandrasekhar method. Eddington-Barbier relation. Physics of gases in stellar atmospheres, ideal gas. Boltzmann law, Maxwell velocity distribution, Saha equation. Thermodynamic equilibrium. Computation of structure of the stellar atmosphere. Grey atmosphere. Extinction processes in astrophysical sources.
Classical dipole absorption, scattering by a classical oscillator. Continuum absorption, H- ion. Rosseland mean opacity. Einstein probabilities. Lasers and masers. Spectral line profiles, equivalent width. Stellar structure. Equation of state of plasma, degenerate electron gas. Nuclear reactions.

Teaching methods

Teaching method Contact Online
Lectures 40 h 0 h
Exercises 16 h 0 h

Teaching language


Modes of study

Option 1
Available for:
  • Degree Programme Students
  • Other Students
  • Doctoral Students
  • Exchange Students
Written exam
  • In English
Participation in classroom work
  • In English

Minimum 1/3 of exercises and the final written exam.

Evaluation and evaluation criteria

Numeric 0-5.
Exercises contribute 30% and the exam 70% to the final grade for the course.

Recommended year of study

3. year spring

For international master students, 1st year of studies, periods III-IV.

Study materials

Lecture notes.
1. Liljeström, T.: Teoreettisen astrofysiikan peruskurssi, lecture note in Finnish.
2. Nilsson, K.: Stellar structure and evolution I (chapters 2-7), lecture notes.
3. Böhm-Vitense, E.: Introduction to Stellar Astrophysics, Vol. 2. Stellar Atmospheres, Cambridge Univ. Press 1989
4. Padmanabhan, T.: Theoretical astrophysics I, Cambridge Univ. Press 2000

Belongs to following study modules

Department of Physics and Astronomy
Department of Physics and Astronomy

Open enrolments

Dec 1, 2017 - Jan 14, 2018
Archived Teaching Schedule. Please refer to current Teaching Shedule.
Department of Physics and Astronomy
Degree Programme in Physical Sciences
DP in Physics Education Track
Degree Programme in Physical Sciences
DP in Theoretical Physics
Finnish Study Modules