universe Review “In-System” Fission-Events: An Insight into Puzzles of Exoplanets and Stars? Elizabeth P. Tito 1,* and Vadim I. Pavlov 2,* 1 Scientific Advisory Group, Pasadena, CA 91125, USA 2 Faculté des Sciences et Technologies, Université de Lille, F-59000 Lille, France * Correspondence:
[email protected] (E.P.T.);
[email protected] (V.I.P.) Abstract: In expansion of our recent proposal 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. Keywords: exoplanets; stellar chemical compositions; nuclear fission; origin and evolution Citation: Tito, E.P.; Pavlov, V.I. “In-System” Fission-Events: An 1. Introduction Insight into Puzzles of Exoplanets As facilities and techniques for astronomical observations and analyses continue to and Stars?. Universe 2021, 7, 118. expand and gain in resolution power, their results provide increasingly detailed information https://doi.org/10.3390/universe about stellar systems, in particular, about the chemical compositions of stellar atmospheres 7050118 and structures of exoplanets.