Upper panel: stars detected in the ACS images (dark dots) are superposed to the stars from the LBT sample of Paper I (gray dots) in a projected coordinate system centered on the center of VV124 and rotated to have the X axis coincide with the major axis of the galaxy (see Paper I). Only stars brighter than I = 26.5 from the ACS sample have been plotted, for clarity. Lower panel: zoomed view of the central part of the ACS sample in the same coordinate system. Two concentric ellipses of semi-major axis a = 1.0′ and a = 1.5′, with the same orientation and ellipticity of the galaxy isophotes (see Paper I) are overplotted (in white and in black, respectively). The white circle has a radius R_p = 40″, enclosing the region studied by J11. Blue stars lying on the young main sequence (YMS; −0.4 ≤ V − I ≤ 0.0 and I < 25.5, see Fig. 3) are plotted as red filled circles, the brightest ones (having I ≤ 23.0) are encircled in orange.