[Fe/H] as a function of the elliptical radius scaled with R_e for Tucana’s probable member stars from the FORS2 combined dataset. Black dots represent the targets with membership probabilities P >  0.95, while the red dots show those with 0.05 <  P <  0.95. The black solid line represents the result of a Gaussian process regression analysis using a Gaussian kernel and taking into account an intrinsic scatter; the gray band indicates the corresponding 1-σ confidence interval. The solid red line and the red band indicate the same, but using all targets with P >  0.05. The histogram on the right side represents the metallicity distribution of the stars with P >  0.95.