  In 1997 Soker laid out a framework for understanding the formation and
shaping of planetary nebulae (PN). Starting from the assumption that
non-spherical PN cannot be formed by single stars, he linked PN morphologies to
the binary mechanisms that may have formed them, basing these connections
almost entirely on observational arguments. In light of the last decade of
discovery in the field of PN, we revise this framework, which, although
simplistic, can still serve as a benchmark against which to test theories of PN
origin and shaping. Within the framework, we revisit the role of planets in
shaping PN. Soker invoked a planetary role in shaping PN because there are not
enough close binaries to shape the large fraction of non-spherical PN. In this
paper we adopt a model whereby only ~20% of all 1-8 solar mass stars make a PN.
This reduces the need for planetary shaping. Through a propagation of
percentages argument, and starting from the assumption that planets can only
shape mildly elliptical PN, we conclude, like in Soker, that ~20% of all PN
were shaped via planetary and other substellar interactions but we add that
this corresponds to only ~5% of all 1-8 solar mass stars. This may be in line
with findings of planets around main sequence stars. PN shaping by planets is
made plausible by the recent discovery of planets that have survived
interactions with red giant branch (RGB) stars. Finally, we conclude that of
the ~80% of 1-8 solar mass stars that do not make a PN, about one quarter do
not even ascend the AGB due to interactions with stellar and substellar
companions, while three quarters ascend the AGB but do not make a PN. Once
these stars leave the AGB they evolve normally and can be confused with
post-RGB, extreme horizontal branch stars. We propose tests to identify them.

Solar and Stellar Astrophysics