Same as Fig. 6 for targets (top to bottom) NGC 7496, NGC 7469, NGC 5990, and NGC 4303. NGC 7496 and NGC 7469 show the same trend as the targets in Fig. 6, i.e. the sites of high density correspond to sites of high star formation. In the case of NGC 7469, the density pattern extends beyond the narrow Hα emission in the S–E direction and a comparison with the reddening map suggests the possibility of obscured star formation. NGC 5990 and NGC 4303, on the other hand, do not show this spatial correlation (see Sects. 4 and 5 for details).