A study of the role of Lyman {\beta} fluorescence on OI line strengths in Be stars

TL;DR

This study investigates the influence of Lyman beta fluorescence on oxygen emission lines in Be stars by comparing observed spectra with theoretical models, confirming the fluorescence mechanism's role.

Contribution

It provides observational evidence and analysis quantifying the impact of Lyman beta fluorescence on OI line strengths in classical Be stars.

Findings

Lyman beta fluorescence contributes to OI line emissions in Be stars.

The observed line ratios support the operation of fluorescence mechanisms.

Multiple excitation processes influence OI line strengths in Be star spectra.

Abstract

The possibility of the Ly{\beta} fluorescence mechanism being operational in classical Be stars and thereby contributing to the strength of the OI 8446 {\AA} line has been recognized for long. However this supposition needs to be quantified by comparing observed and predicted OI line ratios. In the present work, optical and near-infrared spectra of classical Be stars are presented. We analyse the observed strengths of the OI 7774, 8446, 11287 and 13165 {\AA} lines which have been theoretically proposed as diagnostics for identifying the excitation mechanism. We have considered and examined the effects of Ly{\beta} fluorescence, collisional excitation, recombination and continuum fluorescence on these OI line strengths. From our analysis it appears that the Ly{\beta} fluorescence process is indeed operative in Be stars.