The symbiotic and bipolar nebula M2-9: 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
$\sim$ 43 GHz ($\sim$ 7.0 mm) and $\sim$ 345 GHz ($\sim$ 0.9 mm) with angular
resolutions of $\sim$ 0$\rlap{.}^{\prime\prime}$047 and
0$\rlap{.}^{\prime\prime}$09, respectively. The continuum emission at $\sim$ 43
GHz shows an elongated jet-like structure perpendicular to the $\sim$ 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.
