I propose that some irregular `messy’ planetary nebulae (PNe) owe their morphologies to triple-stellar evolution where tight binary systems are tidally and frictionally destroyed inside the envelope of asym
ptotic giant branch (AGB) stars. I estimate that about one in six non-spherical PNe is shaped by one of these triple-stellar evolutionary routes. See paper.
Such is the PN on the right NGC 6210 taken from the HST site.