Coagulation Calculations of Icy Planet Formation at 15--150 AU: A Correlation Between the Maximum Radius and the Slope of the Size Distribution for Transneptunian Objects

TL;DR

This study links coagulation models to observed transneptunian object size distributions, revealing a correlation between maximum object size and distribution slope, and constraining initial conditions for icy planet formation.

Contribution

It establishes a robust relation between the largest object size and size distribution slope, providing testable predictions and constraining initial disk parameters for TNO formation.

Findings

A correlation between maximum radius and size distribution slope for TNOs.

Models with small planetesimals (1-10 km) fit observed data.

Initial disk mass and planetesimal size influence TNO size distribution.

Abstract

We investigate whether coagulation models of planet formation can explain the observed size distributions of transneptunian objects (TNOs). Analyzing published and new calculations, we demonstrate robust relations between the size of the largest object and the slope of the size distribution for sizes 0.1 km and larger. These relations yield clear, testable predictions for TNOs and other icy objects throughout the solar system. Applying our results to existing observations, we show that a broad range of initial disk masses, planetesimal sizes, and fragmentation parameters can explain the data. Adding dynamical constraints on the initial semimajor axis of `hot' KBOs along with probable TNO formation times of 10-700 Myr restricts the viable models to those with a massive disk composed of relatively small (1-10 km) planetesimals.