A detailed model atmosphere analysis of high-resolution and high S/N CCD spectra of II Peg has yielded a self-consistent set of fundamental parameters of the primary component for the first time. In addition, new orbital parameters have been determined. The position of the primary of II Peg in the HR diagram with these new parameters is compatible with the modern evolutionary models for hydrogen-shell-burning stars of mass ~0.9 Msun with low metallicity (Z = 0.008), and corresponds to K2 IV. Combining all parameters, the radius R ~4.5 Rsun and the inclination i ~45 deg of the primary can be estimated under the assumption that its rotational axis is perpendicular to the orbital plane. Also, the nature of the secondary can be deduced from these parameters. It might be a K5 V star with a mass of about 0.7 Msun.
Cool Stars, Stellar Systems, and the Sun
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