Revealing new features of the millimetre emission of the circumbinary
  envelope of Mira Ceti
  We study the morpho-kinematics of the circumbinary envelope of Mira Ceti
between $\sim$100 and $\sim$350 au from the stars using ALMA observations of
the SiO ($\nu$=0, $J$=5-4) and CO ($\nu$=0, $J$=3-2) emissions with the aim of
presenting an accurate and reliable picture of what cannot be ignored when
modelling the dynamics at stake. A critical study of the uncertainties attached
to imaging is presented. The line emissions are shown to be composed of a few
separated fragments. They are described in detail and plausible interpretations
of their genesis are discussed. Evidence for a focusing effect of the Mira A
wind by Mira B over the past century is presented; it accounts for only a small
fraction of the overall observed emission but its accumulation over several
orbital periods may have produced an enhancement of CO emission in the orbital
plane of Mira B. We identify a South-western outflow and give arguments for the
anti-correlation observed between CO and SiO emissions being the result of a
recent mass ejection accompanied by a shock wave. We discuss the failure of
simple scenarios that have been proposed earlier to explain some of the
observed features and comment on the apparent lack of continuity between the
present observations and those obtained in the close environment of the stars.
Evidence is obtained for the presence of large Doppler velocity components near
the line of sight aiming to the star, possibly revealing the presence of
important turbulence at $\sim$5 to 10 au away from Mira A.
