Calibration of iota Pegasi system

Recent observations provide determinations of individual masses, chemical c omposition and metallicity of the components of the spectroscopic and inter ferometric binary iota Peg (Boden et al. 1999). Using updated physics, to c alibrate the system, we have computed using the stellar evolutionary code C ESAM (Morel 1997), evolutionary sequences of stellar models with the masses of iota Peg A 1.326 M-circle dot and i Peg B 0.819 M-circle dot (Boden et al. hoc. cit) and with different values of the mixing-length parameter alph a, the helium Y and the heavy element Z initial mass fraction with the cons traint of the observed metallicity. Adopting effective temperatures and lum inosities, as de roved from observations with the bolometric corrections, a nd the empirical scale of temperatures of Alonso et al. (1995, 1996), we fi nd alpha(A) = 1.46, alpha(B) = 1.36, Y = 0.278, Z = 0.017. The evolution ti me, including pre-main sequence, is found within similar to 40 My less than or similar to t(ev) less than or similar to 0.5 Gy. The calibrated models of iota Peg. A and B are non homogeneous zero age main sequence stars with the evolutionary time t(ev) = 56 My. Due to the large uncertainties of thei r determinations. the values derived for the mixing-length parameters are s maller than the solar one but however marginally compatible with it. Our re sults ought to be improved as soon as a more accurate value of the magnitud e difference in the V filter will be available. Detailed spectroscopic anal ysis for both components looks practicable, so it is urgently needed.