English: Figure 3. (Left-hand panel) Orbital-plane and (right-hand panel) on-sky projections of the geometric wind–wind interface model where dust forms in the colliding winds in the WR 140 binary around periastron passage. The positions of the dust features are overlaid on the model, where the Eastern and Western Arms are on the near side closest to the observer. The orbital parameters of the models are indicated above, and the parameters in the observed view are adopted from the Monnier et al. (2011) results with the Fahed et al. (2011) prior. The half-opening angle of the colliding-wind interface is assumed to be θ ≈ 40°. The appearance of the model corresponds to the timing of the CHARIS observations taken on 2020 September 2 (φ = 0.467) and assumes a constant dust expansion velocity of 2450 km s−1. The orbital configuration of the WR and O stars and the direction of motion of the O star (in the frame of reference of the WR star) is also shown in the models, where the red region indicates the orbital range of active dust formation. The adopted true anomaly range of dust formation is −135° to 135° (Han et al. 2022). The persistent circumstellar dust features are identified in the observed view of the geometric wind–wind interface model, where north is up and east is to the left-hand side.