Astrophysical laser operating in the OI 8446-angstrom line in the Weigelt blobs of eta Carinae

Abstract:
Within the framework of a simple model of photophysical processes in the Weigelt blobs in the vicinity of the luminous blue variable (LBV) star eta Carinae, we explain the presence of the fluorescent < O I > 8446-angstrom and forbidden [O I] 6300-angstrom lines as well as the absence of the allowed O I 7774-angstrom line in spectra recorded with the Hubble Space Telescope (HST)/STIS instrument (Gull et al.). From atomic data and estimated stellar parameters we demonstrate that there is a population inversion and stimulated emission in the 3p P-3-3s S-3 transition lambda 8446 due to photoexcitation by accidental resonance (PAR) by H Ly beta radiation.