Correlations of all the variables with each other in the subset using the stars with the most accurate age determination (see text for details). In the upper triangular part, the Spearman statistic, ρ for each correlation is depicted. The color of the font represents the statistical significance of the correlations depending on the p-value, with red, black, and gray for values with p < 0.001, p < 0.01 and p < 0.1, respectively.In the lower triangular part we also show the spread-plot of each pair of variables, with LOESS fit just to guide the eye.