The collisional ring of NGC5291 and its tidal dwarfs (same as Figure 1) and the rotation curve of one of the TDGs [22]. The observed rotation velocity is too high, and the rotation curve too flat at large radius, to be accounted for by the visible mass distribution alone. Typical 1-sigma error bars are indicated. The rotation curve was measured from HI data and the visible mass estimated from stellar SEDs, HI, and CO data.
