Discovery of a λ Bootis Like Abundance Pattern in the Pulsating Algol-Type System RZ Cassiopeiae

Abstract

The abundances of eight elements (C through Fe) were determined in the primary star of the short-period Algol-type binary RZ Cas relative to the A3 V spectroscopic standard star $\alpha$ PsA. Definite under-abundances (by $-0.45 \,\mathrm{dex}$ or more) of Mg, Si, Ti, Cr, and Fe were established. On the other hand, light elements C and O show solar abundances, and Ca is slightly under-abundant ($\sim-0.3 \,\mathrm{dex}$). This abundance pattern demonstrates that RZ Cas shows a characteristic of mild $\lambda$ Boo-type stars. This finding raises a question on the physical relations between the metallicity (abundance anomaly), the pulsational characteristics, and the mass accretion processes.