Orbit of 2-body model. Top: orbit of (Aa1+Aa2)+Ab components in the (u–v) plane (green), calculated using the two-body model and the simplex method. Observations are shown with blue symbols and uncertainty ellipses (orange). The residuals are plotted in red; the value of χ² = 95. The astrometry used for the fit is from the WDS. The radial velocities of Aa1, from Table 5 were also used for the fit, extending the time span to 44 000 days. Bottom: detail of the observed arc. The most precise astrometric measurements from 2013 and 2019 constrain the orbital period P₂.