GENERATION OF HIGHLY INCLINED TRANS-NEPTUNIAN OBJECTS BY PLANET NINE

Abstract

The trans-Neptunian region of the solar system exhibits an intricate dynamical structure, much of which can be explained by an instability-driven orbital history of the giant planets. However, the origins of a highly inclined, and in certain cases retrograde, population of trans-Neptunian objects remain elusive within the framework of this evolutionary picture. In this work, we show that the existence of a distant, Neptune-like planet that resides on an eccentric and mildly inclined orbit fully accounts for the anomalous component the trans-Neptunian orbital distribution. Adopting the same parameters for Planet Nine as those previously invoked to explain the clustering of distant Kuiper Belt orbits in physical space, we carry out a series of numerical experiments that elucidate the physical process though which highly inclined Kuiper Belt objects with semimajor axes smaller than a  < 100 au are generated. The identified dynamical pathway demonstrates that enigmatic members of the Kuiper Belt such as Drac and Niku are derived from the extended scattered disk of the solar system.