Recent replenishment of aliphatic organics on Ceres from a large subsurface reservoir

Ceres hosts significant aliphatic-organic concentrations, ranging from approximately 5 wt.% to >30 wt.% in specific surface areas. The origins and persistence of these organics are under debate due to the intense aliphatic signature and radiation levels in Ceres' orbit, which would typically lead to their destruction, hindering detection. To investigate this, we conducted laboratory experiments to replicate how the signature of the organic-rich regions would degrade due to radiation. Our findings indicate a fast degradation rate, implying the exposure of buried organics within the last few million years. This degradation rate, coupled with observed quantities, implies that the aliphatics must be present in substantial quantities within the shallow subsurface. Our estimates suggest an initial aliphatic abundance 2-30 times greater than currently observed, surpassing significantly the levels found in carbonaceous chondrites, indicating either a significant concentration or remarkable purity.

Methods
The data set show the modification of the 3.4 micron band under the influence of different energetic sources. the experiments have been conducted at INAF – Osservatorio Astrofisico di Catania (Italy); INAF – Osservatorio Astrofisico di Arcetri (Italy) and INAF – Osservatorio Astrofisico di Napoli(Italy)