The true stellar parameters of the Kepler target list

Using population synthesis tools we create a synthetic Kepler Input Catalogue (KIC) and subject it to the Kepler Stellar Classification Program (SCP) method for determining stellar parameters such as the effective temperature T_eff and surface gravity g. We achieve a satisfactory match between the synthetic KIC and the real KIC in the log g versus log T_eff diagram, while there is a significant difference between the actual physical stellar parameters and those derived by the SCP of the stars in the synthetic sample. We find a median difference ΔT_eff = +500 K and ∼Δlog g = -0.2 dex for main-sequence (MS) stars, and ∼ΔT_eff = +50 K and Δlog g = -0.5 dex for giants, although there is a large variation across parameter space. For a MS star the median difference in g would equate to a ∼3 per cent increase in stellar radius and a consequent ∼3 per cent overestimate of the radius for any transiting exoplanet. We find no significant difference between ΔT_eff and Δlog g for single stars and the primary star in a binary system. We also re-created the Kepler target selection method and found that the binary fraction is unchanged by the target selection. Binaries are selected in similar proportions to single star systems; the fraction of MS dwarfs in the sample increases from about 75 to 80 per cent, and the giant star fraction decreases from 25 to 20 per cent.