(65) Cybele: detection of small silicate grains, water-ice, and organics

The authors show that the surface structure of the primitive asteroid (65) Cybele is covered by a layer of fine anhydrous silicate grains, mixed with smaller quantities of water ice and complex organics, similar to the nonequilibrium phases coexisting on comet surfaces. The co-existence of water ice and anhydrous silicates on the surface indicates that silicate hydration did not occurred, suggesting that the surface temperatures remained low.