Estimates of T_eff and log g for stars in M 67. Error bars denote the errors returned by SME. The yellow circle denotes the solar twin YBP-1194. Blue circles denote blue stragglers. Green circles denote variable stars. White circles denote binary stars. Red circles denote red giants. Black circles denote other stars. The blue curves denote isochrones calculated for the highest and lowest age estimates for the cluster. One star with σ_Teff >  500 K has not been included.