A Study of the Role of Lyβ Fluorescence on O I Line Strengths in Be Stars

Abstract

The possibility of the Lyβ fluorescence mechanism being operational in classical Be (CBe) stars and thereby contributing to the strength of the O I λ8446 line has been recognized for long. However, this supposition needs to be quantified by comparing observed and predicted O I line ratios. In the present work, optical and near-infrared spectra of CBe stars are presented. We analyze the observed strengths of the O I λ7774, λ8446, λ11287, and λ13165 lines, which have been theoretically proposed as diagnostics for identifying the excitation mechanism. We have considered and examined the effects of Lyβ fluorescence, collisional excitation, recombination, and continuum fluorescence on these O I line strengths. From our analysis it appears that the Lyβ fluorescence process is indeed operative in Be stars.