Unravelling the 'Helix' nebula

It is proposed that the complex structures observed in some planetary nebulae may, in part, be due to the focusing action of a binary companion to the star losing mass. Helix-like structures can arise due to orbital precession of the pair under the action of mass loss induced torques. The 'Helix' nebula is presented as a possible example even though duplicity in this object has not yet been observed. (author)