Posterior probabilities after clustering the two overdensities in proper motion space using a two-component Gaussian Mixture Model (GMM). Right panel: all stars in blue have a high probability of belonging to the top left overdenisty in proper motion space, while all stars in red have a high probability of belonging to the lower right overdenisty. Left panel: when visualized in position space, the two proper motion overdensities correspond to the narrow and broad components.