Exoplanet Orbit Shapes Linked to Size: UCLA Study Reveals Formation Pathways

UCLA astrophysicists have determined a correlation between the size and orbital shape of exoplanets using data from NASA's Kepler telescope. The study, published in Proceedings of the National Academy of Sciences, analyzed 1,600 light curves to measure the orbits of exoplanets ranging from Mars-sized to Jupiter-sized. Findings indicate that smaller planets tend to have nearly circular orbits, while larger planets, around the size of Neptune, exhibit orbits that are approximately four times more elliptical. This eccentricity split suggests two distinct formation pathways for small and large planets. The research also notes a coincidence between orbital eccentricity, planet abundance, and stellar metallicity, further supporting the theory of differing formation mechanisms. Larger planets with eccentric orbits suggest a chaotic formation period.