Astronomy8 papers
Binary asteroids
IŽ
Ivana Milić Žitnik
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intermediate
The Strength and Shapes of Contact Binary Objectcts
Alex J. Meyer & Daniel J. Scheeres (2024)
- Published
- Feb 12, 2024
- DOI
- 10.48550/arXiv.2402.07760
At a Glance
Contact binary mergers can occur between rubble piles if secondaries have modest cohesion (∼1–100 Pa) or high friction, shaped by lobe geometry.
Summary
This paper quantifies when a smaller lobe can survive tidal disruption while spiraling into and merging with a larger rubble-pile body to form a contact binary. Using ellipsoidal fits to 11 radar/spacecraft shape models (asteroids, comets, and Arrokoth), it derives strength requirements showing that either a small but nonzero cohesion or a sufficiently large friction angle is typically needed, with inferred cohesive strengths broadly ∼1–100 Pa for a nominal 30° friction angle. The analysis highlights strong dependence on secondary shape: prolate (cigar-like) lobes require substantially more cohesion than oblate (disk-like) lobes, and there are regime “flips” where how cohesion scales with size or density ratio changes near modest asphericities. By comparing contact binaries to binary asteroids and asteroid pairs, the authors argue contact binaries plausibly sit on related evolutionary pathways (e.g., collapsed binaries or failed separations) rather than requiring monolithic components.
Method Snapshot
Apply a Drucker–Prager granular yield criterion to ellipsoid-fitted secondary lobes under tidal/rotational stresses at contact to map friction–cohesion survival thresholds.
Background
Background in small-body dynamics and basic granular/continuum strength models (e.g., friction angle, cohesion, yield criteria) is needed.