Molecules, shocks, and disk in the axi-symmetric wind of the MS-type AGB
  star RS Cancri
  The latest evolutionary phases of low- and intermediate mass stars are
characterized by complex physical processes like turbulence, convection,
stellar pulsations, magnetic fields, condensation of solid particles, and the
formation of massive outflows that inject freshly produced heavy elements and
dust particles into the interstellar medium.
  We use the Northern Extended Millimeter Array (NOEMA) to obtain spatially and
spectrally resolved observations of the semi-regular Asymptotic Giant Branch
star RS Cancri to shed light on the morpho-kinematic structure of its inner,
wind forming environment by applying detailed 3-D reconstruction modeling and
LTE radiative transfer calculations.
  We detect 32 lines of 13 molecules and isotopologs (CO, SiO, SO, SO$_2$,
H$_2$O, HCN, PN), including several transitions from vibrationally excited
states. HCN, H$^{13}$CN, millimeter vibrationally excited H$_2$O, SO,
$^{34}$SO, SO$_2$, and PN are detected for the first time in RS Cnc. Evidence
for rotation is seen in HCN, SO, SO$_2$, and SiO(v=1). From CO and SiO channel
maps, we find an inner, equatorial density enhancement, and a bipolar outflow
structure with a mass loss rate of $1 \times 10^{-7}M_\odot{\rm yr}^{-1}$ for
the equatorial region and of $2 \times 10^{-7}M_\odot{\rm yr}^{-1}$ for the
polar outflows. The $^{12}$CO/$^{13}$CO ratio is measured to be $\sim20$ on
average, $24\pm2$ in the polar outflows and $19\pm3$ in the equatorial region.
We do not find direct evidence of a companion that might explain this kind of
kinematic structure, and explore the possibility that a magnetic field might be
the cause of it. The innermost molecular gas is influenced by stellar pulsation
and possibly by convective cells that leave their imprint on broad wings of
certain molecular lines, such as SiO and SO.
