Near-Infrared Mapping and Physical Properties of the Dwarf-Planet Ceres

TL;DR

This study uses high-resolution near-infrared imaging to determine Ceres' shape, spin, surface features, and mineralogy, revealing detailed physical and compositional properties of the dwarf planet.

Contribution

It provides the first detailed physical and mineralogical mapping of Ceres using adaptive optics near-infrared observations from Keck II.

Findings

Ceres is an oblate spheroid with specific dimensions and spin axis coordinates.

Surface features range from 50 to 180 km with a 6% albedo contrast.

Bright regions contain phyllosilicates and carbonates; darker areas may have frost.

Abstract

We study the physical characteristics (shape, dimensions, spin axis direction, albedo maps, mineralogy) of the dwarf-planet Ceres based on high-angular resolution near-infrared observations. We analyze adaptive optics J/H/K imaging observations of Ceres performed at Keck II Observatory in September 2002 with an equivalent spatial resolution of ~50 km. The spectral behavior of the main geological features present on Ceres is compared with laboratory samples. Ceres' shape can be described by an oblate spheroid (a = b = 479.7 +/- 2.3 km, c = 444.4 +/- 2.1 km) with EQJ2000.0 spin vector coordinates RA = 288 +/- 5 deg. and DEC = +66 +/- 5 deg. Ceres sidereal period is measured to be 9.0741 +/- 0.0001 h. We image surface features with diameters in the 50-180 km range and an albedo contrast of ~6% with respect to the average Ceres albedo. The spectral behavior of the brightest regions on Ceres is consistent with phyllosilicates and carbonate compounds. Darker isolated regions could be related to the presence of frost.