Webb maps 'extreme debris disks' and the planet-shattering collisions that built worlds

NASA’s James Webb Space Telescope has given astronomers their first real crash course on the planet-shattering collisions that build worlds, NASA reported.

A team led by Kate Su of the Space Science Institute in Boulder, Colorado, studied 21 “extreme debris disks” — young stellar systems harbouring unusually large amounts of warm dust close to their star, in the region where rocky planets orbit. The findings were published Thursday in The Astrophysical Journal. Five of the disks came from Spitzer’s archival data and 16 from Webb, with 12 newly observed.

“This is the first time we have gathered enough systems to truly understand this subclass that we call extreme debris disks,” said Su. Only about 1% of young stars show observable signs of this phase.

The team found the disks share three traits — smaller dust grains than in other disks, a high concentration of warm dust, and irregular brightness changes. Their makeup splits into two types: silica-rich disks, about one-third of the sample, produced by high-energy impacts between Mars-sized bodies where much of the rock vaporises; and silica-poor disks, made by grazing collisions between Moon-sized objects. Silica-rich disks appear only around stars younger than 300 million years.

The work echoes our own history: Earth and the Moon formed about 100 million years after the Sun, with the Moon likely born from a collision between Earth and a Mars-sized object. The team says our solar system may have gone through more than one extreme debris disk phase.