Theoretical Astrophysics

absorbing absorption coefficient absorption lines angle approximately Balmer series bright broadening calculations centre Chapter chemical composition chromosphere cm³ collisions Consequently consider constant continuous spectrum contours corona corresponding curve of growth density determined disc distribution element envelope equation of transfer eruption excitation expression fact faculae flux forbidden lines formula free electrons frequency function given helium Hence hydrogen atoms increases integration intensity of radiation interstellar ionisation ionised atoms ions layers luminosity Lyman series mass mean method motion n₁ novae number of atoms observed obtain optical thickness particles photo-ionisation photosphere planetary nebulae processes prominences quantity quantum radiative equilibrium ratio recombination region result scattering solar spectra spectral classes stars of classes stellar atmospheres stellar photospheres Sun's take account theory thermal thermodynamic equilibrium total number transitions velocity wavelength Wolf-Rayet stars