Measuring Apsidal Clustering

Fuente: arXiv
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Auteurs principaux: Siraj, Amir, Chyba, Christopher F., Tremaine, Scott
Format: Preprint
Publié: 2026
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author Siraj, Amir
Chyba, Christopher F.
Tremaine, Scott
author_facet Siraj, Amir
Chyba, Christopher F.
Tremaine, Scott
contents The decade-long debate over the existence of apsidal clustering in the outer solar system is poised for reignition given the plethora of distant trans-Neptunian object (TNO) discoveries expected from the forthcoming Vera C. Rubin Observatory's Legacy Survey of Space and Time (LSST). Here, we present a new conditional-likelihood method to measure apsidal clustering that is insensitive to uneven survey footprints. We calculate the long-term orbital stability of distant TNOs, which allows us to expand the known sample of relevant objects from 21 to 25. We apply our new method to this up-to-date sample, showing that the significance of the apsidal clustering in the outer solar system has fallen from $2.7σ$ to $1.9σ$, and that the direction of clustering is not well constrained. This new method is suitable for application to the growing sample of known TNOs, and the results will reveal whether the evidence for a hypothetical Planet X from apsidal clustering is real or spurious.
format Preprint
id arxiv_https___arxiv_org_abs_2604_25990
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Measuring Apsidal Clustering
Siraj, Amir
Chyba, Christopher F.
Tremaine, Scott
Earth and Planetary Astrophysics
The decade-long debate over the existence of apsidal clustering in the outer solar system is poised for reignition given the plethora of distant trans-Neptunian object (TNO) discoveries expected from the forthcoming Vera C. Rubin Observatory's Legacy Survey of Space and Time (LSST). Here, we present a new conditional-likelihood method to measure apsidal clustering that is insensitive to uneven survey footprints. We calculate the long-term orbital stability of distant TNOs, which allows us to expand the known sample of relevant objects from 21 to 25. We apply our new method to this up-to-date sample, showing that the significance of the apsidal clustering in the outer solar system has fallen from $2.7σ$ to $1.9σ$, and that the direction of clustering is not well constrained. This new method is suitable for application to the growing sample of known TNOs, and the results will reveal whether the evidence for a hypothetical Planet X from apsidal clustering is real or spurious.
title Measuring Apsidal Clustering
topic Earth and Planetary Astrophysics
url https://arxiv.org/abs/2604.25990