The nature and structure of the emission line nebula K 3-35: a very young planetary nebula with precessing bipolar jet-like outflows?

We present H alpha, [N II]6583 and 6-cm continuum images of the emission line nebula K 3-35. The optical images reveal an extended nebula (size similar or equal to 11 x 9 arcsec(2) in [N II]) in which most of the emission originates in a very narrow (width 0.7-1.3 arcsec) S-shaped region which extends almost all along the nebula (similar or equal to 7 arcsec). The 6-cm continuum emission also arises in this narrow region, which is characterized by an exceedingly high point-symmetry and systematic and continuous changes of the orientation with respect to the nebular centre. The properties of the narrow region suggest that it represents a system of precessing bipolar jet-like components. Two low-excitation, compact bipolar knots near the tips of the jet-like components are observed in the deduced [N II]/H alpha image ratio. These knots may be generated by the interaction of the collimated outflows with surrounding material. A comparison of the optical and radio images shows the existence of differential extinction within the nebula. Maximum extinction is observed in a disc-like region which traces the equator of the elliptical shell previously observed at 20-cm continuum. All available data strongly suggest that K3-35 is a very young planetary nebula in which we could be observing the first stages of the formation of collimated outflows and point-symmetric structures typically observed in planetary nebulae. The properties of the jet-like components in K3-35 are in good agreement with models of binary central stars in which highly collimated outflows originate either from a precessmg accretion disc or via magnetic collimation in a precessing star.