Estimating the Density of Intermediate Size KBOs from Considerations of Volatile Retention

TL;DR

This paper develops a hydrodynamic escape model to estimate the density of Kuiper Belt Objects (KBOs) like Quaoar, Orcus, Charon, and Haumea, linking volatile retention with internal structure and rotation.

Contribution

It introduces a novel method to predict KBO densities from volatile detection and internal structure, without requiring binary companion data.

Findings

Predicted Quaoar's high density using hydrodynamic escape mechanisms.

Linked volatile ice presence to body density and size.

Applied the method to constrain densities of 2003 AZ84 and analyze Haumea's internal structure.

Abstract

By using a hydrodynamic atmospheric escape mechanism \citep{amit09} we show how the unusually high mass density of Quaoar could have been predicted (constrained), without any knowledge of a binary companion. We suggest an explanation of the recent spectroscopic observations of Orcus and Charon \citep{delsanti10,cook07}. We present a simple relation between the detection of certain volatile ices and the body mass density and diameter. As a test case we implement the relations on the KBO 2003 AZ$_{84}$ and give constraints on its mass density. We also present a method of relating the latitude-dependence of hydrodynamic gas escape to the internal structure of a rapidly rotating body and apply it to Haumea.