Sky region around 6 Cas (red cross). Top panel: projected offsets on sky. Bottom panel: proper motions. Field stars from Gaia are marked in grey (one in ten is plotted), open clusters from Hunt & Reffert (2024) are marked in coloured points, members of the OB associations Cas OB5 from Mel’nik & Dambis (2017) and no. 141 (Chemel et al. 2022) are marked with open symbols (some members overlap between the two catalogues). The arrows in the top panel indicate the motion of cluster and OB association stars over the past 0.1 Myr based on their proper motions.