2000A&A...357.1031V

Deep narrow band CCD images in the Hα, [OIII]λ5007Å, [NII]λ6584Å, and [SII]λ6717+31Å emission lines have been obtained for the planetary nebula M 2-48. The discovery of a pair of symmetric low-excitation bow-shocks, separated by 4', and forming a highly collimated bipolar outflow, is presented. The bow-shocks are emitting in [OIII] and present the ionization structure expected from working surfaces of collimated jets, pointing out that these structures are tracing regions with shocked gas at high velocities (>100km/s). In addition, an internal bipolar outflow (60''x30'') and an apparent off-center semi-circular shell (size≃110'') are also detected. An enhancement of low-excitation line emission is observed in the shell along the outflow axis. This result can be interpreted in terms of a jet-shell interaction.