On the E 1 Pi-X 1 Sigma + and 1 Sigma +-X 1 Sigma + transitions of ZrO related to S star spectra

Abstract

In view of the prevalent interest in the singlet band systems of ZrO, which are present in the spectra of pure S stars, values of band intensity factors (FCFs) and r-centroids are evaluated and displayed for the e1 Pi - X1 Sigma + and 1 Sigma+ - X1 Sigma + transitions. The results suggest the possible presence of new bands in both the systems and warrant a reinvestigation of the spectrum of ZrO in the 5500-6600 A region. Predicted band head positions of the new bands are presented to aid both laboratory and stellar spectral studies.