A possible origin of the anomaly of the silicon isotopes relative abundance in 67P/Churyumov–Gerasimenko

Cometary objects, such as 67P/Churyumov–Gerasimenko, are thought to have formed or been altered during the protosolar nebula phase of our solar system. In Particular, cometary cores are thought to have formed via accretion of grains and dusts with olivine { (Mg²⁺, Fe²⁺)₂SiO₄} and pyroxene {XY(Si,Al)₂O₆ ) where X,Y = metal ions} being the most common constituent. The recent vidence for depletion of heavy silicon isotopes at comet 67P/Churyumov–Gerasimenko in comparison with solar standard,  is an anomaly that deserves to be investigated.

In the present work we provide a model of the onset of the anomaly based on the nuclear interactions of cometary siliceous dust with simulated solar protons, deuterons and neutrons.