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Dynamical Evolution Induced by Planet Nine

Batygin, Konstantin and Morbidelli, Alessandro (2017) Dynamical Evolution Induced by Planet Nine. Astronomical Journal, 154 (6). Art. No. 229. ISSN 1538-3881. doi:10.3847/1538-3881/aa937c.

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The observational census of trans-Neptunian objects with semimajor axes greater than ~250 au exhibits unexpected orbital structure that is most readily attributed to gravitational perturbations induced by a yet-undetected, massive planet. Although the capacity of this planet to (i) reproduce the observed clustering of distant orbits in physical space, (ii) facilitate the dynamical detachment of their perihelia from Neptune, and (iii) excite a population of long-period centaurs to extreme inclinations is well-established through numerical experiments, a coherent theoretical description of the dynamical mechanisms responsible for these effects remains elusive. In this work, we characterize the dynamical processes at play from semi-analytic grounds. We begin by considering a purely secular model of orbital evolution induced by Planet Nine and show that it is at odds with the ensuing stability of distant objects. Instead, the long-term survival of the clustered population of long-period Kuiper Belt objects (KBOs) is enabled by a web of mean-motion resonances driven by Planet Nine. Then, by taking a compact-form approach to perturbation theory, we show that it is the secular dynamics embedded within these resonances that regulate the orbital confinement and perihelion detachment of distant KBOs. Finally, we demonstrate that the onset of large-amplitude oscillations of the orbital inclinations is accomplished through the capture of low-inclination objects into a high-order secular resonance, and we identify the specific harmonic that drives the evolution. In light of the developed qualitative understanding of the governing dynamics, we offer an updated interpretation of the current observational data set within the broader theoretical framework of the Planet Nine hypothesis.

Item Type:Article
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URLURL TypeDescription Paper
Batygin, Konstantin0000-0002-7094-7908
Additional Information:© 2017 The American Astronomical Society. Received 2017 August 10; revised 2017 October 2; accepted 2017 October 3; published 2017 November 16. We are thankful to Mike Brown, Greg Laughlin, Chris Spalding, Matt Holman, Gongjie Li, Tali Khain, and Elizabeth Bailey for illuminating discussions. Additionally, we are grateful to Sarah Millholland for providing a thorough and insightful referee report, as well as to Charles Fairchild, whose generous support facilitated this collaboration.
Group:Astronomy Department
Subject Keywords:celestial mechanics; Kuiper belt: general
Issue or Number:6
Record Number:CaltechAUTHORS:20171121-090705606
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Official Citation:Konstantin Batygin and Alessandro Morbidelli 2017 AJ 154 229
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:83387
Deposited By: Tony Diaz
Deposited On:21 Nov 2017 17:15
Last Modified:15 Nov 2021 19:57

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