A mirror-symmetric jet in the bipolar nebula M 2-9

We show that the compact radio core of the bipolar nebula M 2-9 has the spectral and spatial properties of a biconical ionized jet. Moreover, this jet exhibits mirror symmetry, with its two lobes pointing in the directions of mirror-symmetric brightenings in the nebular lobes. Such a jet is required by models that invoke a symbiotic star system at the center of M 2-9 to explain the nebular properties. In these models, the impact of the jet on the walls of the nebular lobes, or the weaker attenuation of ionizing radiation from the WD star along two paths cleared by the jet in the AGB star wind, creates the bright mirror-symmetric features in the nebula. The lateral motion of these features is attributed to changes in the jet direction due to the orbital motion of the central binary system.