The Reflectance Spectra of CV-CK Carbonaceous chondrites from the Near Infrared to the Visible

TL;DR

This study measures and compares the near-infrared to visible reflectance spectra of CV and CK carbonaceous chondrites, revealing their common origin and effects of thermal metamorphism and space weathering on their spectral properties.

Contribution

It provides detailed spectral data for CV and CK chondrites across petrologic types, linking their properties to asteroid origins and collisional evolution.

Findings

CV and CK chondrites share a common parent asteroid reservoir.

Spectral differences reflect varying degrees of thermal metamorphism.

Both groups likely originated from the 221 Eos asteroid family.

Abstract

Carbonaceous chondrite meteorites are so far the only available samples representing carbon-rich asteroids and in order to allow future comparison with samples returned by missions such as Hayabusa 2 and OSIRIS-Rex, is important to understand their physical properties. Future characterization of asteroid primitive classes, some of them targeted by sample-return missions, requires a better understanding of their mineralogy, the consequences of the exposure to space weathering, and how both affect the reflectance behavior of these objects. In this paper, the reflectance spectra of two chemically-related carbonaceous chondrites groups, precisely the Vigrano (CVs) and Karoonda (CKs), are measured and compared. The available sample suite includes polished sections exhibiting different petrologic types: from 3 (very low degree of thermal metamorphism) to 5 (high degree of thermal metamorphism). We found that the reflective properties and the comparison with the Cg asteroid reflectance class point toward a common chondritic reservoir from which the CV-CK asteroids collisionally evolved. In that scenario the CV and CK chondrites could be originated from 221 Eos asteroid family, but because of its collisional disruption, both chondrite groups evolved separately, experiencing different stages of thermal metamorphism, annealing and space weathering.