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PřF:F7600 Physics of stellar atmospheres - Course Information

## F7600 Physics of stellar atmospheres

**Faculty of Science**

Autumn 2018

**Extent and Intensity**- 2/1. 3 credit(s) (fasci plus compl plus > 4). Type of Completion: zk (examination).
**Teacher(s)**- doc. RNDr. Jiří Kubát, CSc. (lecturer)

Mgr. Barbora Doležalová (seminar tutor) **Guaranteed by**- prof. RNDr. Zdeněk Mikulášek, CSc.

Department of Theoretical Physics and Astrophysics - Physics Section - Faculty of Science

Contact Person: doc. RNDr. Jiří Kubát, CSc.

Supplier department: Department of Theoretical Physics and Astrophysics - Physics Section - Faculty of Science **Timetable**- Mon 17. 9. to Fri 14. 12. Tue 8:00–10:50 FLenc,03028
**Prerequisites**- Completion of courses in quantum and statistical physics is recommended.
**Course Enrolment Limitations**- The course is offered to students of any study field.
**Course objectives**- The aim of this course is to introduce students to basics of radiation-matter interaction, transfer of radiation, and to methods applied to solution of these problems in astrophysics.
**Learning outcomes**- After completion of the course the students will:

- understand the radiation-matter interaction in astrophysics
- know limits of using equilibrium distributions in astrophysics
- know various methods of solution the transfer of radiation and their suitability to different astrophysical applications
- be able to use models based on the assumption of kinetic equilibrium (NLTE)
- be able to attend follow-up courses and seminars
**Syllabus****Basic concepts**(specific intensity, photon number density, photon distribution function, equilibrium distribution, mean intensity, flux, radiation pressure tensor, radiation energy, basic quantities in plane-parallel and spherical geometry, description of polarized radiation**Radiation transfer equation**(absorption coefficient, emission coefficient, scattering, derivation of radiative transfer equation, mean free photon path, optical depth, source function, boundary conditions for the transfer equation, moments of the transfer equation, transfer equation for polarized radiation**Thermodynamic equilibrium**(Maxwellian velocity distribution, Boltzmann excitation formula, Saha ionization formula, dissociation of molecules, state equation with ionization, determination of electron density, local thermodynamic equilibrium)**Absorption and emission in lines**(Einstein coefficients, oscillator strength, cross section, spectral line profiles, natural broadening, Doppler broadening, Voigt profile, microturbulence, collisional broadening, Stark broadening, atomic structure and transitions of hydrogen and hydrogen-like ions, atomic structure and line transitions of light elements, levels in a magnetic field, interaction of radiation with molecules)**Absorption and emission in continuum**(ionization and recombination, Einstein-Milne relations for continuum, continuum cross section, free-free transitions)**Scattering**(conitnuum scattering on free and bound electrons, scattering in spectral lines, redistribution function)**Solution of the radiatie transfer equation**diffusion approximation, lambda operator, formal solution of the radiative transfer equation, discretization of the transfer equatiobn, long characteristics method, short characteristics method, Feautrier method, solution of moment equations, solution using the Monte Carlo method)**Solution of the radiative transfer equation in a moving medium**(transfer equation in the observer frame and in the comoving frame, Sobolev approximation, P Cyg profile)**Radiative transfer with scattering**(thermalization length, direct methods of solution (integral methods, differential methods), iteration methods of solution (variable Eddington factors method))**Collision processes**(ionization and excitation by collisions with electrons, other collisional processes, Auger ionization)**Kinetic (statistical) equilibrium equations**(radiative rates (bound-bound transitions, photoionization transitions), collisional rates, occupation probabilities, system of equations of kinetic (statistical) equilibrium (linear dependence and supplementary equations), limit and special cases (one-level atom with continuum, cascade transitions, level fine structure in the interstellar medium)**Solution of the NLTE problem**(two-level atom without continuum and with continuum, thermalization length in spectral lines, lambda iteration, accelerated lambda iteration, solution of a multilevel atom using the complete linearization method and using the accelerated lambda iteration, basic NLTE efects in lines and continua, density matrix)

**Literature**- KUBÁT, Jiří.
*Fyzika hvězdných atmosfér a větrů*, učební text - HUBENÝ, Ivan and Dimitri MIHALAS.
*Theory of stellar atmospheres : an introduction to astrophysical non-equilibrium quantitative spectroscopic analysis*. Princeton, N.J.: Princeton University Press, 2015. xvi, 923. ISBN 9780691163291. info - MIHALAS, Dimitri.
*Stellar atmospheres*. 2nd ed. San Francisco: W.H. Freeman and Company, 1978. xx, 632. ISBN 0716703599. info - RYBICKI, George B. and Alan P. LIGHTMAN.
*Radiative processes in astrophysics*. New York: John Wiley & Sons, 1979. xv, 382. ISBN 0471827592. info - PRADHAN, Anil a Sultana NAHAR.
*Atomic Astrophysics and Spectroscopy*, Cambridge University Press, 2011, ISBN9780521825368

*recommended literature*- JEFFERIES, John T.; Spectral line formation, Blaisdel Publ. Comp., 1968

*not specified*- KUBÁT, Jiří.
**Teaching methods**- Lecture and exercise
**Assessment methods**- Oral exam.
**Language of instruction**- Czech
**Follow-Up Courses****Further Comments**- Study Materials

The course is taught annually.

- Enrolment Statistics (Autumn 2018, recent)
- Permalink: https://is.muni.cz/course/sci/autumn2018/F7600