The chemical composition and circumstellar environment of the variable star QY sge

Abstract

Chemical composition studies of the variable star QY Sge show abundance anomalies suggestive of the pattern exhibited by the warmer RV Tau variables. Abundance analysis indicates a near-solar atmosphere with highly condensable elements depleted by several factors. Evidence of broad Na D emission features in its spectrum, a characteristic feature of RCrB stars taken at minimum, however, raises the question of its spectral classification. We address this question through a comparative analysis of its spectrum with those of gamma Cyg, 89 Her and R CrB taken at minimum., in addition to abundance analysis. We also discuss a possible physical scenario of the circumstellar environment accounting for the characteristics of the distinct spectroscopic features.