Unveiling Ceres’ surface composition: Insights from the 1.2 micron band and aqueous alteration processes
Filippo Giacomo Carrozzo, Maria Cristina De Sanctis, Andrea Raponi, Marco Ferrari, Mauro Ciarniello, Eleonora Ammannito
Icarus, In Press, Journal Pre-proof, Available online 17 March 2026
“Highlights
- Global mapping of Ceres’ 1.2 μm band using Dawn/VIR data.
- The 1.2 μm band anticorrelates with phyllosilicate absorptions.
- Hapke modeling identifies magnetite as the main contributor.
- Results support widespread aqueous alteration on Ceres.
- The 1.2 μm band center is stable, while its depth varies regionally.”
“Ceres, the largest object in the asteroid belt, exhibits a complex surface composition shaped by extensive aqueous alteration. Using co-registered visible and infrared (0.25–5.2 μm) data from the Dawn/VIR spectrometer, we mapped and characterized the broad 1.2 μm absorption feature across the dwarf planet to elucidate its mineralogical diversity and evolutionary history. Our analysis reveals that this band, centered at 1.2 ± 0.04 μm, is globally distributed with band depths ranging from 3% to 10%. The 1.2 μm feature shows an anticorrelation with both the 0.7 μm reflectance and the phyllosilicate bands at 2.7 and 3.1 μm, suggesting that its carrier partially masks hydrated-phase signatures. Spectral modeling using Hapke radiative transfer theory identifies magnetite as the most plausible contributor to this feature, indicating its widespread yet uneven distribution, possibly driven by localized hydrothermal processes. The presence of magnetite as a key spectral contributor offers new insights into Ceres’ surface mineralogy and its evolution as a volatile-rich, endogenously altered body. This research advances our understanding of water-driven alteration processes in the asteroid belt and provides a foundation for future exploration of Ceres’ surface composition and evolutionary history.”
