Contribution of a > 80 AU TNOs to Kuiper Belt Mean Plane Measurements

Determine the contribution of trans-Neptunian objects with barycentric semimajor axis greater than 80 AU to measurements of the Kuiper belt’s mean plane when using a 50–150 AU semimajor-axis bin, distinguishing their effect from the more numerous objects with 50–80 AU to assess their specific influence on the inferred mean plane relative to the invariable plane.

Background

Prior work measured the Kuiper belt’s mean plane in the 50–150 AU semimajor-axis range and found consistency with the invariable plane. However, that bin is numerically dominated by objects with 50–80 AU, leaving the influence of the more distant population poorly constrained.

Clarifying the role of objects with a > 80 AU is important for understanding whether the distant Kuiper belt’s mean plane aligns with the invariable plane or exhibits a warp that could indicate new dynamical influences, such as an unseen planet.

References

However, this bin is dominated in number by objects with semimajor axes in the range 50 - 80 AU, so it is unclear what the contribution from objects with a > 80 AU is.

— Measuring the Mean Plane of the Distant Kuiper Belt  (2508.14156 - Siraj et al., 19 Aug 2025) in Introduction

A central Layer-2 design question is therefore what minimum combination of depth, field of view, survey area, ecliptic and off-ecliptic coverage, and revisit cadence is required to distinguish a flattened trans-Neptunian population from one evolving toward isotropy with increasing heliocentric distance, while retaining sensitivity to rare large bodies at hundreds to thousands of au.

— Small-Body Science with the Nautilus Space Observatory: From Cislunar Space Resilience to Mapping the Kuiper-Belt-to-Oort-Cloud Transition  (2609.10663 - Wit et al., 9 Sep 2026) in Section 3.2, subsection “Layer 2: Deep search and characterization”