KINEMATICAL EVIDENCE FOR A ROTATING, EPISODIC JET IN THE PLANETARY-NEBULA FLEMING-1

Spatially resolved, long-slit, echelle observations have been obtained in the light of the Halpha and [N II] lambda6548 emission lines for the symmetric strings of ionized knots emerging from the body of the elliptical planetary nebula Fleming 1. It is found that the magnitudes of the radial velocity differences of both strings systematically increase away from the nebular center. The north string is redshifted, whereas the south string is blue-shifted. The radial velocity difference from tip to tip of the north and south strings is 148 km s-1. The data are reasonably consistent with a simple ballistic model that assumes episodic ejections of collimated, bipolar flows emerging from a rotating source. These observations confirm some of the theoretical predictions of Soker (1992).