Webb maps collision chemistry in 21 debris disks

A team led by Kate Su of the Space Science Institute published in The Astrophysical Journal the first large-sample compositional census of 21 "extreme debris disks" using JWST's MIRI. The study identifies two chemically distinct collision types: silica-rich impacts between Mars-sized bodies, found only around stars younger than about 300 million years, and silica-poor collisions between Moon-sized bodies across a wider age range.

• 21 disks studied: 5 from Spitzer archives, 16 observed by Webb, 12 in detail for the first time
• About 38% of disks are silica-rich, indicating Mars-sized impacts
• Silica-rich disks appear only around stars younger than roughly 300 million years
• The other two-thirds are silica-poor, pointing to Moon-sized collisions