Spectral reflectance analysis of type 3 carbonaceous chondrites and search for their asteroidal parent bodies

Non-differentiated asteroids are among the most primitive objects in our Solar System, having escaped intense heating mechanisms. To help us understand the information contained in reflectance spectra measured on asteroids, we analyzed meteorites in the laboratory. We present an in-depth analysis of a large set of reflectance spectra: 23 CV3, 15 CO3, 4 CR2 and 31 Unequilibrated Ordinary Chondrites (UOCs). Each of the samples has a well characterized thermal history . Variations in the reflectance spectra are observed between and within each chondrite group. UOCs systematically exhibit deeper absorption features, distinguishing them from carbonaceous chondrites. The CR2 samples presented in this study are easily distinguished from type 3 chondrites by exhibiting the 1 mu m band at lower wavelengths. CV and CO chondrites exhibit comparable mineralogical compositions and can, therefore, not be distinguished solely based on their spectral features. In the case of CV chondrites, the 1 mu m band depth increases with increasing metamorphic grade, while among CO chondrites, the spectra exhibit increasing visual slopes. By comparing the chondrite spectra with the spectra of various end member asteroids we are able to suggest several possible genetic links to the studied chondrites. The method in this work is supported by observed match between UOC and S-type asteroid spectra. A further link is found between CV/CO chondrites and Eos and L-type asteroids. Finally, CK chondrite spectral features match with Eos and K-type asteroids. Lastly, we underline the potential of the 3 mu m band to constrain asteroid-meteorite links.

Automated summary

By analyzing the reflectance spectra of a variety of chondrites, differences between and within different types of chondrites were observed. For example, UOCs exhibit deeper absorption features compared to other types, while CR2 samples are easily distinguished by showing the 1 micron band at lower wavelengths.