Understanding the trans-Neptunian Solar system: Reconciling the results of serendipitous stellar occultations and the inferences from the cratering record
arXiv:2111.00391 · doi:10.1051/0004-6361/202040267
Abstract
The most pristine remnants of the Solar system's planet formation epoch orbit the Sun beyond Neptune, the small bodies of the trans-Neptunian object populations. The bulk of the mass is in ~100 km objects, but objects at smaller sizes have undergone minimal collisional processing, with New Horizons recently revealing that ~20 km effective diameter body (486958) Arrokoth appears to be a primordial body, not a collisional fragment. This indicates bodies at these sizes (and perhaps smaller) retain a record of how they were formed, and are the most numerous record of that epoch. However, such bodies are impractical to find by optical surveys due to their very low brightnesses. Their presence can be inferred from the observed cratering record of Pluto and Charon, and directly measured by serendipitous stellar occultations. These two methods produce conflicting results, with occultations measuring roughly ten times the number of ~km bodies inferred from the cratering record. We use numerical models to explore how these observations can be reconciled with evolutionary models of the outer Solar system. We find that models where the initial size of bodies decreases with increasing semimajor axis of formation, and models where the surface density of bodies increases beyond the 2:1 mean-motion resonance with Neptune can produce both sets of observations, though comparison to various observational tests favours the former mechanism. We discuss how to evaluate the astrophysical plausibility of these solutions, and conclude extended serendipitous occultation surveys with broad sky coverage are the most practical approach.
Accepted version, to appear in Astronomy & Astrophysics
References in corpus (18)
- Origin of the Structure of the Kuiper Belt during a Dynamical Instability in the Orbits of Uranus and Neptune
- The timeline of the Lunar bombardment - revisited
- Variations on Debris Disks: Icy Planet Formation at 30-150 AU for 1-3 Solar Mass Main Sequence Stars
- Turbulence sets the length scale for planetesimal formation: Local 2D simulations of streaming instability and planetesimal formation
- Solution to the debris disc mass problem: planetesimals are born small?
- Formation of bi-lobed shapes by sub-catastrophic collisions: A late origin of comet 67P/C-G's structure
- Coupling dynamical and collisional evolution of small bodies II : Forming the Kuiper Belt, the Scattered Disk and the Oort Cloud
- Amateur telescopes discover a kilometre-sized Kuiper belt object from stellar occultation
- Discovery of A New Retrograde Trans-Neptunian Object: Hint of A Common Orbital Plane for Low Semi-Major Axis, High Inclination TNOs and Centaurs
- A Search for sub-km KBOs with the Method of Serendipitous Stellar Occultations
- A re-assessment of the Kuiper belt size distribution for sub-kilometer objects, revealing collisional equilibrium at small sizes
- Not a simple relationship between Neptune's migration speed and Kuiper belt inclination excitation
- A serendipitous all sky survey for bright objects in the outer solar system
- Rocky Planetesimal Formation via Fluffy Aggregates of Nanograins
- Eccentric Early Migration of Neptune
- Modeling the Formation of the Family of the Dwarf Planet Haumea
- Oort cloud asteroids: Collisional evolution, the Nice Model, and the Grand Tack
- Low-cost precursor of an interstellar mission