Where are the missing Kuiper Belt binaries?

Fuente: arXiv
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Main Author: Lyra, Wladimir
Format: Preprint
Published: 2025
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author Lyra, Wladimir
author_facet Lyra, Wladimir
contents In this letter, we call attention to a gap in binaries in the Kuiper belt in the mass range between $\approx$10$^{19}$-10$^{20}$ kg, with a corresponding dearth in binaries between 4th and 5th absolute magnitude $H$. The low-mass end of the gap is consistent with the truncation of the cold classical population at 400 km, as suggested by the OSSOS survey, and predicted by simulations of planetesimal formation by streaming instability. The distribution of magnitudes for all KBOs is continuous, which means that many objects exist in the gap, but the binaries in this range have either been disrupted, or the companions are too close to the primary and/or too dim to be detected with the current generation of observational instruments. At the high-mass side of the gap, the objects have small satellites at small separations, and we find a trend that as mass decreases, the ratio of primary radius to secondary semimajor increases. If this trend continues into the gap, non-Keplerian effects should make mass determination more challenging.
format Preprint
id arxiv_https___arxiv_org_abs_2507_08948
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Where are the missing Kuiper Belt binaries?
Lyra, Wladimir
Earth and Planetary Astrophysics
In this letter, we call attention to a gap in binaries in the Kuiper belt in the mass range between $\approx$10$^{19}$-10$^{20}$ kg, with a corresponding dearth in binaries between 4th and 5th absolute magnitude $H$. The low-mass end of the gap is consistent with the truncation of the cold classical population at 400 km, as suggested by the OSSOS survey, and predicted by simulations of planetesimal formation by streaming instability. The distribution of magnitudes for all KBOs is continuous, which means that many objects exist in the gap, but the binaries in this range have either been disrupted, or the companions are too close to the primary and/or too dim to be detected with the current generation of observational instruments. At the high-mass side of the gap, the objects have small satellites at small separations, and we find a trend that as mass decreases, the ratio of primary radius to secondary semimajor increases. If this trend continues into the gap, non-Keplerian effects should make mass determination more challenging.
title Where are the missing Kuiper Belt binaries?
topic Earth and Planetary Astrophysics
url https://arxiv.org/abs/2507.08948