Physical Characterization of 2015 JD1: A Possibly Inhomogeneous Near-Earth Asteroid

TL;DR

This study provides a comprehensive physical characterization of near-Earth asteroid 2015 JD1, revealing its complex surface, contact-binary shape, and compositional heterogeneity through radar, spectroscopy, and photometry.

Contribution

First detailed physical analysis of 2015 JD1 combining radar, spectral, and photometric data, highlighting its complex morphology and surface composition variations.

Findings

2015 JD1 is a contact-binary asteroid approximately 150 m in size.

Surface shows spectral variation from red to blue, indicating compositional heterogeneity.

Asteroid likely originated from the ν6 resonance, similar to E-type asteroid progenitors.

Abstract

The surfaces of airless bodies such as asteroids are exposed to many phenomena that can alter their physical properties. Bennu, the target of the OSIRIS-REx mission, has demonstrated how complex the surface of a small body can be. In 2019 November, the potentially hazardous asteroid 2015 JD1 experienced a close approach of 0.0331 au from the Earth. We present results of the physical characterization of 2015 JD1 based on ground-based radar, spectroscopy, and photometric observations acquired during 2019 November. Radar polarimetry measurements from the Arecibo Observatory indicate a morphologically complex surface. The delay-Doppler images reveal a contact-binary asteroid with an estimated visible extent of ~150 m. Our observations suggest that 2015 JD1 is an E-type asteroid with a surface composition similar to aubrites, a class of differentiated enstatite meteorites. The dynamical properties of 2015 JD1 suggest it came from the $\nu_6$ resonance with Jupiter, and spectral comparison with major E-type bodies suggest that it may have been derived from a parental body similar to the progenitor of the E-type (64) Angelina. Significantly, we find rotational spectral variation across the surface of 2015 JD1 from red to blue spectral slope. Our compositional analysis suggests that the spectral slope variation could be due to the lack of iron and sulfides in one area of the 2015 JD1 and/or differences in grain sizes.