Ice older than its star
The James Webb telescope found water ice in the Beta Pictoris system, 64 light-years away. The researchers concluded the ice most likely formed in the interstellar medium, long before the planets of Beta Pictoris began to take shape. This 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. This finding contradicts models predicting that ice in debris disks should mostly be crystalline. Because the ice is amorphous, it must remain colder than 100 Kelvin, or minus 173° Celsius, to prevent its structure from breaking up. The absence of a sharp peak in the spectrum just above 3 micrometers confirms that most molecules did not settle into an orderly crystal lattice.
| Feature | Specification |
|---|---|
| Distance to Beta Pictoris | 64 light-years |
| Crystalline ice percentage | Less than 7% |
| Temperature for amorphous ice | Below 100 Kelvin (-173°C) |
| Spectral peak absence | Above 3 micrometers |
Collision-driven dust replenishment
The team argues that the even distribution of ice across the disk requires frequent collisions among planetesimals. Such collisions release fresh icy dust. This dust includes ice that had been buried and protected deep inside the colliding bodies, which replenishes what starlight destroys. Earlier infrared images revealed a curved, lopsided streak of dust in the southwestern arm of the disk, which researchers thought was debris from a violent collision a little less than halfway out from the star. These findings support the idea that the disk’s carbon monoxide gas comes from colliding icy bodies and explain how ice survives in an environment constantly exposed to ultraviolet light.
Betti’s team could not determine exactly how much crystalline ice exists in the system or rule out other molecules hiding in the mixture. This lack of precision is a significant limitation in characterizing the chemical makeup of the debris disk. If this young planetary system started with the same icy ingredients as our own, then primordial, interstellar ice might be a common ingredient of planetary systems in general. This means the raw materials for water-rich, potentially habitable worlds might be common, too.
