High Precision Photometry of Extreme KBO 2003 EL61

TL;DR

This study provides high-precision, time-resolved photometry of Kuiper belt object 2003 EL61, revealing rapid rotation, subtle color variations, and a large surface region with distinct albedo and color, indicating surface heterogeneity.

Contribution

First detailed high-precision photometric analysis of 2003 EL61 revealing surface heterogeneity and rotational properties.

Findings

Rapid rotation period of 3.9155 hours.

Detection of subtle, reproducible color variations.

Identification of a large surface region with different albedo and color.

Abstract

We present high precision, time-resolved visible and near infrared photometry of the large (diameter ~ 2500 km) Kuiper belt object (136108) 2003 EL61. The new data confirm rapid rotation at period P = 3.9155+/-0.0001 hr with a peak-to-peak photometric range (Delta m_R) = 0.29+/-0.02 mag and further show subtle but reproducible color variations with rotation. Rotational deformation of 2003 EL61 alone would give rise to a symmetric lightcurve free of color variations. The observed photometric deviations from the best-fit equilibrium model show the existence of a large surface region with an albedo and color different from the mean surface of 2003 EL61. We explore constraints on the nature of this anomalous region set by the existing data.