Metal Abundance of the Eclipsing Binary YZ Cas
/ Authors
E. Lastennet, D. Valls-Gabaud, C. Valongo, Ufrj, R. Janeiro, Brazil, A. Unit, Qmw, London, U. Omp
and 3 more authors
/ Abstract
We review current and new estimates of the eclipsing binary YZ Cassiopeiae metallicity (Z). Since the individual components cover a quite large range of mass (1.35–2.31M⊙), YZ Cas is potentially one of the best stellar laboratories to understand the structure and evolution of 1 to 2 M⊙ stars. The derivation of Z from IUE spectra, as well as from photometric indices, provides the chemical composition of the atmosphere (Zatmospheric), while the fit of evolutionary tracks provides the initial chemical composition (Zinitial). While a disagreement is expected between Zatmospheric and Zinitial because the primary component is an Am star (one expects Zatmospheric to be larger), we find some unexpected discrepancy between atmospheric determinations of Z for this star.