Page 2 - 83 basic knowledge of astronomy
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8 Emission and Absorption of Electromagnetic Radiation 13
8.1 Elementary Quantum Theory of Radiation (A. Einstein, 1916) 13
8.2 Einstein Coefficients . . . . . . . . . . . . . . . . . . . . . . . 17
8.3 Number Density of Photons . . . . . . . . . . . . . . . . . . . 17
9 Blackbody Radiation 18
9.1 Two Extreme Cases of the Planck Spectrum . . . . . . . . . . 20
9.2 Wien’s Law . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
9.3 Spectral Indices of Thermal Continuum Radio Sources . . . . 22
9.4 Stars are Faint and Gas Clouds are Bright in the Radio Sky . 22
9.5 Stefan–Boltzmann Law . . . . . . . . . . . . . . . . . . . . . . 24
9.6 Total Blackbody Radiation from a Star or a Gas Cloud . . . . 24
9.7 Universality of the Relationship among Einstein’s Coefficients 25
9.8 Another Important Quantity in Radio Astronomy . . . . . . . 26
10 Radiative Transfer 26
10.1 Phenomenological Derivation of the Radiative Transfer Equation 26
10.2 Derivation of the Radiative Transfer Equation from Einstein’s
Elementary Quantum Theory of Radiation . . . . . . . . . . . 27
10.3 The Simplest Solutions of Radiative Transfer Equation . . . . 28
10.4 What is LTE? . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
10.5 Spectrum of the Orion Nebula . . . . . . . . . . . . . . . . . . 33
11 Synchrotron Radiation 34
11.1 Non–Relativistic Case . . . . . . . . . . . . . . . . . . . . . . 34
11.2 Relativistic Case . . . . . . . . . . . . . . . . . . . . . . . . . 36
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