A compositional interpretation of TNO taxonomy

Grant #: NNX12AM75G
Senior Scientist: Cristina Dalle Ore

In the trans-Neptunian region, ices are common and clearly detectable in the largest trans-Neptunian objects (TNOs). However, it is the small TNOs at the far edge of the Solar System, pristine in composition because of their distance, that could contribute important information on the original composition of the system. The proposed research consists in an investigation aimed at: 

a) understanding systematics of TNO composition and surface alteration, including quantification and discrimination of ices, dark material and minerals to unfold the chemical evolution of the outer Solar System 

b) studying the origin of the dark material, whether or not organic in nature, in relation to the hydrocarbon and water ice availability. 

c) forming a baseline for future studies of planetary systems: an accurate determination of the current (and past) composition of the outer Solar System will allow us to infer its chemical properties, to be compared to similar regions around other planetary systems. 

d) define a set of color filters that could best resolve ambiguities in the ice composition of TNOs and Centaurs. 


Because of their sizes and distances, small TNOs can only be observed photometrically. In previous work we demonstrated how a statistical analysis (taxonomy) of selected broadband photometric data, has yielded preliminary information on the chemistry of the surface of TNOs thanks to the addition of albedo information. We propose to adopt the same approach, this time tuned to distinguish among ices by extending the wavelength range of our scope to include the signature of ices common on the surface of TNOs.