No Need for Planet 9

Anne-Marie Madigan (UC Berkley)

May 05, 2016

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Abstract: The orbits of extreme Kuiper Belt Objects (KBOs) are distributed in a bizarre, unprecedented manner. They all have high inclinations, tilt asymmetrically in the same way, and cluster in argument of pericenter. In addition, many are “detached” from the inner solar system, which cannot be explained through gravitational scattering. One explanation is due to gravitational perturbations from an as-of-yet undiscovered Neptune-mass planet in our outer solar system: “Planet 9”. In this talk, I will show that Planet 9 is not necessary to explain their structure. Self-gravity acting between KBOs can explain their observed distribution. This is due to a new dynamical instability in Keplerian disks composed of bodies on eccentric orbits.