Jindřich Žižka | Searcharxiv

arXiv2026

Young asteroid pair candidates in the Jovian Trojan population

The number of asteroid pairs, unbound asteroids with a common origin and similar heliocentric orbits, has increased rapidly since their discovery. However, to date, only a small number of asteroid pairs have been identified in the outer main belt and especially within the Hilda and Jupiter Trojan populations. Except for a few binaries and collisional families, only one 360 Myr-old pair (258656) 2002 ES76 - (635224) 2013 CC41 is known among the Jupiter Trojans. During our survey, using GPU-accelerated integrations of the Jovian swarms, we identified two new promising pair candidates younger than 2.5 Myr. Pair (264119) Georgeorton - 2024 CN most likely formed either 427-500 kyr or 527-536 kyr ago, whereas pair (8060) Anius - (542262) 2013 BL has an estimated age of 2367-2421 kyr. Our results show that young asteroid pairs can arise even within the sparse population of Jupiter Trojans, opening new questions about their formation.

astro-ph.EP↗

arXiv2014

Observations of "Fresh" and Weathered Surfaces on Asteroid Pairs and Their Implications on the Rotational-Fission Mechanism

The rotational-fission of a rubble-pile asteroid can result in an "asteroid pair", two un-bound asteroids sharing similar orbits. This mechanism might exposes material that previously had never have been exposed to the weathering conditions of space. Therefore, the surfaces of asteroid pairs offer the opportunity to observe non-weathered fresh spectra. We report near-IR spectroscopic observations of 31 asteroids in pairs. We analyze their spectral slopes, 1 μm absorption band, taxonomy, and estimate the time elapsed since their separation. Analyzing the 19 S-complex objects in our sample, we find two fresh Q-type asteroids that are the first of their kind to be observed in the main-belt over the full visible and near-IR range. This solidly demonstrates that Q-type objects are not limited to the NEA population. The pairs in our sample present a range of fresh and weathered surfaces with no clear evidence for a correlation with the ages of the pairs. However, our sample includes old pairs (1 to 2 My) that present low spectral slopes. This illustrates a timescale of at least ~2 My before an object develops high spectral slope that is typical for S-type asteroids. We discuss mechanisms that explain the existence of weathered pairs with young dynamical ages and find that the "secondary fission" model (Jacobson & Scheeres 2011) is the most robust with our observations since: 1) the secondary members in our sample present fresh parameters that tend to be fresher than their weathered primaries; 2) most of the fresh pairs in our sample have low size ratios between the secondary and the primary; 3) 33% of the primaries in our sample are fresh, similar to the prediction set by this model; 4) known satellites orbit two of the pairs in our sample with low size ratio and fresh surface; 5) there is no correlation between the weathering state and the primary shape as predicted by other models.

astro-ph.EP↗