Lunar-like silicate material forms the Earth quasisatellite (469219) 2016 HO3 Kamo`oalewa

TL;DR

This study characterizes the Earth quasi-satellite Kamo`oalewa, revealing a lunar-like silicate composition and suggesting it may be composed of lunar material due to space weathering effects.

Contribution

First comprehensive physical analysis of Kamo`oalewa using telescopic observations, identifying its lunar-like silicate composition and potential lunar origin.

Findings

Kamo`oalewa has a rotation period of approximately 28.3 minutes.

Its reflectance spectrum indicates a lunar-like silicate composition.

The spectral analysis suggests extensive space weathering on Kamo`oalewa.

Abstract

Little is known about Earth quasi-satellites, a class of near-Earth small solar system bodies that orbit the sun but remain close to the Earth, because they are faint and difficult to observe. Here we use the Large Binocular Telescope (LBT) and the Lowell Discovery Telescope (LDT) to conduct a comprehensive physical characterization of quasi-satellite (469219) Kamo`oalewa and assess its affinity with other groups of near-Earth objects. We find that (469219) Kamo`oalewa rotates with a period of 28.3 (+1.8/-1.3) minutes and displays a reddened reflectance spectrum from 0.4-2.2 microns. This spectrum is indicative of a silicate-based composition, but with reddening beyond what is typically seen amongst asteroids in the inner solar system. We compare the spectrum to those of several material analogs and conclude that the best match is with lunar-like silicates. This interpretation implies extensive space weathering and raises the prospect that Kamo`oalewa could comprise lunar material.