  In expansion of our recent proposal (Physics, 2020, 2, 213-276) that the
solar system's evolution occurred in two stages -- during the first stage, the
gaseous giants formed (via disk instability), and, during the second stage
(caused by an encounter with a particular stellar-object leading to "in-system"
fission-driven nucleogenesis), the terrestrial planets formed (via accretion)
-- we emphasize here that the mechanism of formation of such stellar-objects is
generally universal and therefore encounters of such objects with
stellar-systems may have occurred elsewhere across galaxies. If so, their
aftereffects may perhaps be observed as puzzling features in the spectra of
individual stars (such as idiosyncratic chemical enrichments) and/or in the
structures of exoplanetary systems (such as unusually high planet densities or
short orbital periods). This paper reviews and reinterprets astronomical data
within the "fission-events framework." Classification of stellar systems as
"pristine" or "impacted" is offered.
