Astrophysics 4 Bifurcation (mathematics) Ionization 4 Mathematical models 4 Optical bistability 4 Parameter estimation 4 Radiation 4 Stars: early-type 4 Stars: mass-loss 4 Stars: rotation 4 Stars: winds, outflows 4 Stars:early-type 4 Stars:mass-loss 4 Stars:rotation Stars:winds, outflows 4 Temperature measurement 4 Velocity measurement 4