(a) v_LOS vs. r_⊥. The solid line represents the relationship when the QSFs are confined to a thin spherical shell near the SN blast wave at r = 170″ and expand radially at 300 km s⁻¹. (b) v_LOS vs. v_μ. The solid lines represent the relationship when the QSFs expand radially at 100 or 300 km s⁻¹. In both panels, the dotted horizontal lines mark the systemic LOS velocity of the Cas A SNR. Blue symbols indicate Group 1 QSFs, while magenta symbols represent Group 2 QSFs. Radial velocities are adopted from A. Alarie et al. (2014) (see Table 2).