NSF-DOE Vera C. Rubin Observatory's First View of the Neptune Trojan L5 (Trailing) Cloud: Two New Long-Term Stable Trojans
Abstract
The NSF-DOE Vera C. Rubin Observatory's combination of survey speed, sky coverage, and depth provides a unique opportunity to study the distant Trans-Neptunian region, including the Neptune Trojans. The Neptune Trojans are small bodies on orbits with Neptune's semimajor axis that are locked in the 1:1 mean motion resonance librating about the ice giant's stable Lagrange points, L4 (leading) and L5 (trailing), located 60∘ ahead of or behind the planet. For more than 15 years, the on-sky location of the L5 Neptune Trojan cloud has been coincident with the Galactic plane and Galactic center; the high stellar density has significantly hindered the discovery of L5 Neptune Trojans. In 2025, the L5 cloud has now moved sufficiently out of the galactic plane to overlap with the sky covered by Rubin Observatory's Science Validation (SV) survey that was executed during the Observatory's commissioning phase. We report on two new confirmed long-term stable (primordial) members of the Neptune L5 Trojan cloud (2025 MH348 and 2025 NN80), doubling the known sample, and one candidate (2025 MD138) that have been found in a preliminary search of the SV survey observations. We present our study to characterize the physical and dynamical properties of these objects and compare the L5 sample to the well-studied L4 cloud. This work also presents the first characterization of objects discovered by Rubin Observatory's moving object discovery pipelines using observations taken in an LSST-like cadence and as such, provides a blueprint for LSST-era analyses.
Versions
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BibTeX
@misc{schwamb2026nsfdoe,
title = {{NSF-DOE Vera C. Rubin Observatory's First View of the Neptune Trojan L5 (Trailing) Cloud: Two New Long-Term Stable Trojans}},
author = {Megan E. Schwamb and Pedro H. Bernardinelli and Kathryn Volk and Joseph Murtagh and Hsing Wen Lin and Andrew S. Rivkin and Colin Orion Chandler and R. Lynne Jones and Susan D. Benecchi and Mario Jurić and Jacob A. Kurlander and Sarah Greenstreet and Adam Wilson and Maxine West and Ryan R. Lyttle},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.38309},
eprint = {2610.38309},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.38309},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - NSF-DOE Vera C. Rubin Observatory's First View of the Neptune Trojan L5 (Trailing) Cloud: Two New Long-Term Stable Trojans
AU - Megan E. Schwamb
AU - Pedro H. Bernardinelli
AU - Kathryn Volk
AU - Joseph Murtagh
AU - Hsing Wen Lin
AU - Andrew S. Rivkin
AU - Colin Orion Chandler
AU - R. Lynne Jones
AU - Susan D. Benecchi
AU - Mario Jurić
AU - Jacob A. Kurlander
AU - Sarah Greenstreet
AU - Adam Wilson
AU - Maxine West
AU - Ryan R. Lyttle
PY - 2026
DA - 2026/10/28
PB - arXiv
DO - 10.48550/arxiv.2610.38309
UR - https://arxiv.org/abs/2610.38309
AB - The NSF-DOE Vera C. Rubin Observatory's combination of survey speed, sky coverage, and depth provides a unique opportunity to study the distant Trans-Neptunian region, including the Neptune Trojans. The Neptune Trojans are small bodies on orbits with Neptune's semimajor axis that are locked in the 1:1 mean motion resonance librating about the ice giant's stable Lagrange points, L4 (leading) and L5 (trailing), located 60^∘ ahead of or behind the planet. For more than 15 years, the on-sky location of the L5 Neptune Trojan cloud has been coincident with the Galactic plane and Galactic center; the high stellar density has significantly hindered the discovery of L5 Neptune Trojans. In 2025, the L5 cloud has now moved sufficiently out of the galactic plane to overlap with the sky covered by Rubin Observatory's Science Validation (SV) survey that was executed during the Observatory's commissioning phase. We report on two new confirmed long-term stable (primordial) members of the Neptune L5 Trojan cloud (2025 MH348 and 2025 NN80), doubling the known sample, and one candidate (2025 MD138) that have been found in a preliminary search of the SV survey observations. We present our study to characterize the physical and dynamical properties of these objects and compare the L5 sample to the well-studied L4 cloud. This work also presents the first characterization of objects discovered by Rubin Observatory's moving object discovery pipelines using observations taken in an LSST-like cadence and as such, provides a blueprint for LSST-era analyses.
ER -