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. 
Henri M. J. Boffin, Brent Miszalski, Thomas Rauch, David Jones, Romano   L. M. Corradi, Ralf Napiwotzki, Avril C. Day-Jones,...
astro-ph.GA astro-ph.SR physics.comp-ph