An Interacting Binary System Powers Precessing Outflows of an Evolved
  Star
  Stars are generally spherical, yet their gaseous envelopes often appear
non-spherical when ejected near the end of their lives. This quirk is most
notable during the planetary nebula phase when these envelopes become ionized.
Interactions among stars in a binary system are suspected to cause the
asymmetry. In particular, a precessing accretion disk around a companion is
believed to launch point-symmetric jets, as seen in the prototype Fleming 1.
Our discovery of a post common-envelope binary nucleus in Fleming 1 confirms
that this scenario is highly favorable. Similar binary interactions are
therefore likely to explain these kinds of outflows in a large variety of
systems.
