2000MNRAS.311..748M

We present high-resolution echelle and long-slit spectra and broad-band (R, I) images of the very young planetary nebula K3-35. Several emission lines are identified, including the Heii4686 line and strong [Nii]6548, 6583 and [Oiii]4959, 5007 emissions [I([Nii])/I(Hα)≃5.5, I([Oiii])/I(Hβ)≃30]. A systemic velocity V_LSR≃10±2km.s^–1 for K3-35 is obtained from the optical emission lines. Two different kinematic components are identified in the nebula. One of them is probably related to the elliptical envelope previously observed. The second component exhibits systematic changes of the radial velocity with position, and a relatively small velocity width. This component may be attributed to the precessing jet-like outflows previously identified. The R and I images and the deduced R-I colour map strongly support the existence of a dense, partially neutral disc-like region in the equatorial plane of the nebula, which probably represents an equatorial density enhancement in a previously ejected slow wind. Diagnostic diagrams for line intensity ratios in K3-35 and collimated components of other planetary nebulae suggest that the emission spectrum of this kind of structure is a combination of radiative and shock excitation, in agreement with recent models of shocks in a strongly photoionized medium.