Pi gruis - molecular identifications and spectral classification

Abstract

Identifications of the molecular absorption features in the visible spectrum of the S star Pi Gruis are presented. Moderate dispersion spectrum of π/sup1 Gru covering the region 5800-7300 Å, demonstrates the presence of a multitude of molecular bands. Wavelength measures of well over 150 red-degraded band heads are listed. Nearly 80% of the observed features are identified with the ZrO, LaO, YO, and CeO molecules. Neither TiO molecular features nor any Ba compounds are detectable. As a consequence of the presence of bands due to s-process oxides and the absence of TiO bands, π/sup1 Gru may be classified as a pure S star.