Distribution of Pearson coefficients after randomly drawing 10⁵ samples from the data shown in Fig. 1. Left: 2D Gaussians centered at our data points and with σ equal to our error bars. The green, red, and blue areas show the 68, 95, and 99% confidence intervals, respectively. The black line shows the observed coefficient. Right: 2D Gaussians centered at random locations of the parameter space (age between 0 and 7 Myr and σ_1D between 0 and 80 km s⁻¹) and with σ equal to our error bars. The blue shaded area represents the probability (2%) that the observed coefficient is caused by a random distribution.