The structure of the water ice also pointed in this direction. When water freezes at moderate temperatures, its molecules settle into an orderly crystal lattice, and crystalline ice produces a sharp peak in the spectrum just above 3 micrometers. That peak was absent at Beta Pictoris. The ice is almost entirely amorphous, a disordered, glass-like solid that forms when water molecules freeze so fast and so cold that they stick wherever they land. The team estimates that less than 7 percent of the water ice in the system is crystalline, which is somewhat surprising.
Models predicted that ice in debris disks should mostly be crystalline. For amorphous ice to
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