Quaoar: A Rock in the Kuiper belt

TL;DR

This study reports detailed orbital and physical characteristics of the Quaoar-Weywot Kuiper belt binary, revealing Quaoar's high density and providing new size and mass estimates through observations and analysis.

Contribution

The paper presents the first detailed orbital parameters and physical properties of the Quaoar-Weywot system, including a high-density estimate for Quaoar, based on new observational data.

Findings

Weywot has an elliptical orbit with eccentricity 0.14

Quaoar's diameter is approximately 890 km

Quaoar's density is estimated at 4.2 g/cm^3

Abstract

Here we report WFPC2 observations of the Quaoar-Weywot Kuiper belt binary. From these observations we find that Weywot is on an elliptical orbit with eccentricity of 0.14 {\pm} 0.04, period of 12.438 {\pm} 0.005 days, and a semi-major axis of 1.45 {\pm} 0.08 {\times} 104 km. The orbit reveals a surpsingly high Quaoar-Weywot system mass of 1.6{\pm}0.3{\times}10^21 kg. Using the surface properties of the Uranian and Neptunian satellites as a proxy for Quaoar's surface, we reanalyze the size estimate from Brown and Trujillo (2004). We find, from a mean of available published size estimates, a diameter for Quaoar of 890 {\pm} 70 km. We find Quaoar's density to be \rho = 4.2 {\pm} 1.3 g cm^-3, possibly the highest density in the Kuiper belt.