Separation distribution for stars and BDs in the model (curves, Sect. 3.2) in comparison with observational data on stellar binarity in Taurus (symbols with errors; Kraus et al. 2011; Daemgen et al. 2015). The Daemgen et al. (2015) data are constructed using the physically bound pairs among 64 targets associated with Taurus (their Table 2, see Sect. 2). The solid curves show the initial BD and stellar late-type population in the model. The dashed curves depict the resulting distributions after allowing for little evolution in the Taurus-Auriga groups (see Sect. 3.2). The BD distributions result from the addition of BDs from both IMF branches (Fig. 1).