The symbiotic and bipolar nebula M 2-9: Morphological variability of the collimated ionized wind arising from the core

We studied the central region of bipolar nebula M 2-9 using radio-continuum observations obtained from the Jansky Very Large Array (JVLA) and the Atacama Large Millimeter Array (ALMA) interferometers. This work presents new images at ~43 GHz (~7.0 mm) and ~345 GHz (~0.9 mm) with angular resolutions of $\sim {0{^{\prime \prime}_{.}}047}$ and ${0{^{\prime \prime}_{.}}09}$, respectively. The continuum emission at ~43 GHz shows an elongated jet-like structure perpendicular to the ~345 GHz observation. We conclude that both emissions could correspond to tracing an isothermal collimated fast wind with constant expansion velocity and being driven by the circumstellar ring traced by ALMA. Although this configuration has been discussed within the scope of planetary nebulae models, there is a remarkable fact: the collimated fast wind shows morphological spatial variability. This supports the idea of a symbiotic binary system within the innermost part of M 2-9, which would be composed of a white dwarf and an AGB star. The latter could explain the mirror symmetry observed at larger scales due to their orbital motion.