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Course, academic year 2018/2019
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Astrophysics I - NAST013
Title in English: Astrofyzika I
Guaranteed by: Astronomical Institute of Charles University (32-AUUK)
Faculty: Faculty of Mathematics and Physics
Actual: from 2015 to 2019
Semester: winter
E-Credits: 6
Hours per week, examination: winter s.:4/0 Ex [hours/week]
Capacity: unlimited
Min. number of students: unlimited
State of the course: taught
Language: Czech
Teaching methods: full-time
Guarantor: doc. RNDr. Martin Šolc, CSc.
prof. RNDr. Jan Palouš, DrSc.
Mgr. Daniela Korčáková, Ph.D.
Classification: Physics > Astronomy and Astrophysics
Annotation -
Last update: prof. RNDr. David Vokrouhlický, DrSc. (10.01.2019)
Thermodynamics of gas and radiation, Boltzmann and Saha equation, Einstein coefficients. Interstellar matter, formation and evolution of stars. Optical, infrared and radio observations. Distribution of interstellar matter in the Galaxy, molecular clouds, neutral hydrogen, interstellar dust. Multicomponent model of interstellar gas, the role of supernovae. Collaps of interstellar clouds, shock waves, fragmentation, star formation, open stellar clusters and associations. Early phases of stellar evolution.Origin of planetary systems.Dynamics and chemical evolution of galaxies,galactic population.
Literature - Czech
Last update: prof. RNDr. David Vokrouhlický, DrSc. (10.01.2019)

Scheffler H., Elsasser H.: Physics of the Galaxy (kap. 4.-5.), Springer, Heidelberg 1987

Spitzer L.: Physical Processes in the Interstellar Medium, J. Willey and Sons, New York 1978

Whittet D.C.B.: Dust in the Galactic Environment, IoP, Bristol 1992

Harwitt M.: Astrophysical Concepts, J. Willey and Sons, New York 1973

Vanýsek V.: Základy astronomie a astrofyziky, Academia Praha 1980ihvezdném plynu a hvezdných atmosférách.

Teaching methods - Czech
Last update: T_AUUK (31.03.2008)


Requirements to the exam - Czech
Last update: Mgr. Daniela Korčáková, Ph.D. (13.10.2017)

Předmět je zakončen zkouškou, která má písemnou a ústní část.

Písemná část se skládá z vypracování přidělených témat, které zahrnuje odvození základních vztahů a srozumitelný slovní popis problému. Písemnou část je možné po částech odevzdávat během semestru, nikoliv těsně před zkouškou.

Ústní část se skládá z vysvětlení zvolené definice a dílčího problému, přehledové otázky z oboru spektroskopie a jedné otázky z oboru fyziky mezihvězdné látky.

Syllabus -
Last update: prof. RNDr. David Vokrouhlický, DrSc. (10.01.2019)
1. Formation and properties of spectral lines (D. Korčáková)
Radiative transfer equation (RTE): General form, planparallel form (stellar atmosphere), formal solution of the radiative transfer equation in the planparallel geometry for the elementary cases - vacuum, homogeneous absorbing layer.

Thermodynamic equilibrium: Local thermodynamic equilibrium (LTE), Boltzmann and Saha equation, non-LTE, equation of statistical equilibrium - bound-bound, bound-free and free-free transitions.

Einstein coefficients and Planck law. Classical oscillator approximation, effective cross-sections, oscillator strength - gf, application to hydrogen.

Opacity and emissivity.

Profiles of spectral lines: Natural broadening, pressure broadening, thermal broadening, Voigt profile, observed line profiles.

Radiation transfer and effects influencing the line profile: Microturbulence, macroturbulence. Rotation - stellar rotation (+ limb darkening). Accretion disks. Stellar wind. Magnetic field - Zeeman split. Instrumental profile.

Curve of growth.

2. Interstellar matter in the Galaxy (M. Šolc)
Interstellar dust

Absorption, radiation transfer in absorbing clouds, optical thickness, absorption coefficient, geometric and effective cross-section, column density. Mean free path of photons. Extiction, color index, color excess. Extinction curve, normalized extinction curve. Dark dust clouds, Wolf diagram. Globules. Diffuse interstellar bands, correlation between equivalent width of bands and extinction. Scattering and absorption of light on dust particles, summary of the Mie's theory. Albedo. Thermal emission of dust, Planck law and laws resulting from it - Rayleigh-Jeans law, Wien's law, Wien's displacement law, Stefan-Boltzmann law.

Interstellar polarization. Stokes parameters, Poincaré sphere, scattering matrix, relationship between the degree of linear polarization and the size of dust grains. Orientation of dust particles in magnetic field, Davis-Greenstein mechanism. Reflection nebulae, diffuse galactic light. Galactic magnetic field as source for interstellar polarization.

Interstellar gas

Stationary lines in the spectra of binaries, the discovery of interstellar gas. Ultraviolet absorption, spectral lines of multiply ionized elements. Hydrogen molecule and UV radiation. Radioastronomy - Rayleigh-Jeans law, antena temperature. The flux unit Jansky. Definition of brightness temperature. Spectral index. The difference between thermal and non-thermal radiation.

Neutral hydrogen and its line on 21 cm. Galactic rotation and the distribution of H I - regions. Brightness temperature on 21 cm plotted in galactic coordinates. Zeeman splitting of 21cm-line and galactic magnetic field.

Electrons in interstellar space, Faraday rotation of linearly polarized radiation, dependence on the wavelength, rotation measure. Dispersion measure. Concentration of free electrons along the line of sight.

Scattering of photons by free electrons and by atoms and molecules.

Giant molecular clouds. CO as tracer of hydrogen molecules, mapping of gas content in galaxies.

Radiation field in interstellar space. Concentration of photons; spectrum of dispersed UV, X and gamma radiation. Cosmic rays, energetic spectrum, concentration.

Interstellar molecules - spectra, formation and dissociation, main chemical reactions on grains and in gas, isotopes and fractionation.

H II regions, excitation, ionization, Strömgren radius. IR and radio observations. Example - the Great Nebula in Orion (M42). Metastable energy levels, forbidden transitions. Physical characteristics of H II regions. Free-free transitions in hot interstellar gas and thermal radio continuum.

Circumstellar envelopes of young stars. Planetary nebulae.

Supernova remnants, adiabatic and isothermic expansion, shock waves. Stellar winds, mass loss from star as depending on spectral class and evolution stage.

Heating and cooling of interstellar matter.

3. Star formation (J. Palouš)
Neutral hydrogen H I in the interstellar space

Emission line 21 cm, width and complex profile, interpretation of radial velocities, Aro, kinematic distances and their uncertainties, rotation curves, massive haloes, the total mass of our Galaxy and where to search for the dark matter. Optical depth, Rayleigh-Jeans law, brightness temperature, radiation transfer, column density, distribution in spiral galaxies.

Molecular hydrogen in the interstellar space

Stability of hydrogen molecule, observations of molecule CO, column densities, molecular clouds, sites of star formation, anomal distribution of H I.

Five phases of interstellar gas, the role of supernovae.

Star forming regions. Shock waves and triggering th gravitational collaps of interstellar clouds. Jeans criterion, subsequent fragmentation. Initial mass function, ZAMS. Virial theorem, Helmholtz-Kelvin contraction. Differences between stars of Population I and II. Evolution of stars with different masses.

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