Eyes in the sky: Interactions between AGB winds and the interstellar
  magnetic field
  We aim to examine the role of the interstellar magnetic field in shaping the
extended morphologies of slow dusty winds of Asymptotic Giant-branch (AGB)
stars in an effort to pin-point the origin of so-called eye shaped CSE of three
carbon-rich AGB stars. In addition, we seek to understand if this pre-planetary
nebula (PN) shaping can be responsible for asymmetries observed in PNe.
Hydrodynamical simulations are used to study the effect of typical interstellar
magnetic fields on the free-expanding spherical stellar winds as they sweep up
the local interstellar medium (ISM). The simulations show that typical Galactic
interstellar magnetic fields of 5 to 10 muG, are sufficient to alter the
spherical expanding shells of AGB stars to appear as the characteristic eye
shape revealed by far-infrared observations. The typical sizes of the simulated
eyes are in accordance with the observed physical sizes. However, the eye
shapes are of transient nature. Depending on the stellar and interstellar
conditions they develop after 20,000 to 200,000yrs and last for about 50,000 to
500,000 yrs, assuming that the star is at rest relative to the local
interstellar medium. Once formed the eye shape will develop lateral outflows
parallel to the magnetic field. The "explosion" of a PN in the center of the
eye-shaped dust shell gives rise to an asymmetrical nebula with prominent
inward pointing Rayleigh-Taylor instabilities.
  Interstellar magnetic fields can clearly affect the shaping of wind-ISM
interaction shells. The occurrence of the eyes is most strongly influenced by
stellar space motion and ISM density. Observability of this transient phase is
favoured for lines-of-sight perpendicular to the interstellar magnetic field
direction. The simulations indicate that shaping of the pre-PN envelope can
strongly affect the shape and size of PNe.
