Near-ultraviolet (panel a) and far-ultraviolet (panel b) images of Arp 240 taken from GALEX archive. The J image (panel c) and K image (panel d) from 2MASS (Skrutskie et al. 2006). The 4.5 μm (panel e) and 8 μm (panel f) images taken with Spitzer-IPAC camera (Smith et al. 2007); 12 μm (panel g) image taken with WISE-PAC Wright et al. (2010); IRSA catalogue); 24 μm (panel h) image taken with Spitzer-MIPS (Smith et al. 2007); 60 μm (panel i) and 160 μm (panel j) images taken with Herschel “blue” channel and “red” channel, respectively (Proposal ID KPGT esturm 1). Ellipses indicate the location of the bifurcation radius, R_bif, in the rotation curve of NGC 5257, discussed in Sects. 4.3, 4.5, and 4.6. North is to the top, east is to the left.