Spectroscopic studies of R CrB during light minima - Absorption spectrum

Abstract

R CrB was observed during the 1986 shallow minimum to study the spectral changes taking place during light minimum as compared with the spectrum at maximum light. The absorption spectrum at this minimum is very similar to the spectrum seen during the early decline of the 1963 light minimum. An enhancement of molecular bands of C2, CN, and low excitation atomic lines is found during these phases. An absorption feature at 4050.5A is also noted, probably due to C3 in the early decline of the 1963 and 1986 minima. Calculations do not indicate any drastic change in effective temperature and microturbulence between light maximum and minimum. It appears that regions with enhanced molecular absorptions are required to explain the absorption spectrum during light minimum.