Non-Coherent Scattering in Stellar Atmospheres

Non-Coherent ScatteringinStellar Atmospheres P. Heinzel

S=B

Multilevel atoms Special new problems Absorption profile for a two-level atom known, f1=fM (Voigt fct) For a three-level atom, transition 2 -> 3, NOT known since f2 will differ from fM due to a selective absorption Emission profile for transition 3 -> 2 also NOT known, f3 also differs from fM For CRD we have fi=fM

Natural population • Spontaneous emission • Inellastic collisions • Ionization and recombination • Excitation by frequency-independent radiation -> i *

Generalized redistribution functions Finite number of atomic levels -> finite number of non-Markovian radiation processes 1*=>2=>3 … =>n->I GRF describe photon correlations in each sequence of consecutive radiation transitions of the atom that starts from naturally populated initial level

Emission in the transition 3->1 (L) • ->3*->1 prob{->3*} • 1*=>3->1 prob{1*=>3} • ->2*=>3->1 prob{->2*=>3} • 1*=>2=>3->1 prob{1*=>2=>3}

Absorption in the transition 2=>3 (H) • -> 2* => 3 prob{->2*} • 1*=>2=>3 prob{1*=>2}

Solution of the transfer problem • Generalized redistribution functions • Multilevel cases • General approach • Solution of the transfer problem (2-level atom, ETLA, ETLA+LINEAR, MALI) • Applications

Non-Coherent Scattering in Stellar Atmospheres