(a)–(b)–(c) Vector point diagrams for the samples shown in the corresponding panels below. (d) CMD of the sources in panel (s1) of Fig. 3. In all panels, sources within the WD region (between the two green lines) are represented in blue, while all other sources are shown in orange. The light grey and dark grey shaded areas indicate the 5σ and 3σ limit, respectively, of significant detection for the sources of interest. (e) One-dimensional PM, μ_R, as a function of the m_F606W magnitude. Bright stars (down to m_F606W ∼ 28) exhibit a μ_R distribution with a tight dispersion (< 1.5 mas yr⁻¹), along with a tail displaying a much broader dispersion. We arbitrarily define two regions, indicated by the red line: one enclosing the bulk of the μ_R values at different magnitudes (indicated by filled circles), and the other containing objects with larger μ_R (indicated by crosses). (f)–(g) CMDs for the stars within and beyond the red line defined in panel (e). Neither of the two CMDs solely consists of members or field objects (see text for details).