Stellar Flyby Sculpted the Orbits and Colors of Trans-Neptunian Objects

New research suggests a stellar flyby in the early solar system shaped the unusual orbits and color distribution of trans-Neptunian objects (TNOs). Using supercomputer simulations, scientists modeled a 0.8 solar mass star's flyby of the protoplanetary disk, successfully reproducing the spiral arm-like distribution of TNOs, their orbital characteristics, and their red-to-gray color gradient. The simulations showed a correlation between color and orbital inclination, with red objects primarily found at low inclinations and green to blue objects dominating higher inclinations. This research provides new evidence for a stellar flyby in the early solar system and offers predictions for future Vera Rubin Observatory observations, promising a deeper understanding of solar system formation.