Morphology and expansion characteristics of the planetary nebula M 1-79.

In this paper we present deep broad- and narrow-band images (JohnsonB, Gunn-red, Hα, Hα+[NII], [NII], [OIII]) and high resolution spectroscopy (Fabry-Perot interferometer (Hα, Hβ, [NII], [OIII]) and Coude measurements (Hα, [NII])) for the planetary nebula (PN) M 1-79. Systemic and expansion velocities are investigated along with the morphological characteristics of this PN. M 1-79 exhibits an elliptical central region surrounded by a bipolar structure (lobes) which is probably much more extended than previously known. Various symmetry axes of the projected shape of this PN are discussed with respect to a three dimensional model. Two axes cannot be explained by projection effects. They give evidences for ejections along different axes during the formation process of this PN. A possible scenario of the evolutionary process of M 1-79 is discussed.