A paper by graduate student Armaan Goyal, titled “Enhanced Size Uniformity for Near-Resonant Planets”, has recently been accepted for publication in the Astrophysical Journal!
It has been demonstrated thoroughly that planets orbiting the same star tend to be extremely similar in their mass, size, and orbital spacing, exhibiting a surprising “peas-in-a-pod” structure that is remarkably different from what we see in our own solar system. Although this trend has been characterized by various studies, various questions still remain with regard to its nature: Why is this trend so common? What is its physical origin? What can it tell us about how planets and planet systems form in general?
Armaan’s work attempts to probe some of these exact questions by considering this peas-in-a-pod trend separately for two different populations: “near-resonant” systems where at least two planets have nearly-synchronized orbital periods (e.g. an one planet orbits three times in the same duration it’s outer neighbor orbits twice), and “non-resonant” systems where none of the planets show this kind of synchronization. By applying a variety of statistical tests to 299 planet systems from the California Kepler Survey, Armaan’s paper demonstrates that planets with these nearly-synchronized orbits tend to be more uniform in size than planets without these resonances, and that this trend exists both across entire planet systems and even for individual pairs of planets orbiting the same star!
Armaan’s findings add valuable information to our current understanding of how planets form and evolve in general. His results broadly support planet formation theories in which neighboring planets are born with synchronized orbits before losing these resonances either from mild interactions with their birth environments, or from more violent interactions with other planets.
This work was conducted in collaboration with Professor Fei Dai at Caltech, as well as IU’s own Professor Songhu Wang. The full paper can be found at:
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