The large-scale nebular pattern of a superwind binary in an eccentric
  orbit
  Preplanetary nebulae and planetary nebulae are evolved, mass-losing stellar
objects that show a wide variety of morphologies. Many of these nebulae consist
of outer structures that are nearly spherical (spiral/shell/arc/halo) and inner
structures that are highly asymmetric (bipolar/multipolar). The coexistence of
such geometrically distinct structures is enigmatic because it hints at the
simultaneous presence of both wide and close binary interactions, a phenomenon
that has been attributed to stellar binary systems with eccentric orbits. Here
we report new high-resolution molecular-line observations of the circumstellar
spiral-shell pattern of AFGL 3068, an asymptotic giant branch star
transitioning to the preplanetary nebula phase. The observations clearly reveal
that the dynamics of the mass loss is influenced by the presence of an
eccentric-orbit binary. This quintessential object opens a new window on the
nature of deeply embedded binary stars through the circumstellar spiral-shell
patterns that reside at distances of several thousand Astronomical Units from
the stars.
