New data from Webb confirms long-proposed planet formation process

NASA's premium space science observatory, the James Webb Space Telescope (JWST), has confirmed a long-standing physical process of planet formation. Scientists have long theorized that icy pebbles that form in outer regions of protoplanetary disks drift from the outer to the inner regions of the disk, delivering both water and solids that form planets.

"Webb finally revealed the connection between water vapor in the inner disk and the drift of icy pebbles from the outer disk. This finding opens up exciting prospects for studying rocky planet formation with Webb" said principal investigator Andrea Banzatti of Texas State University, San Marcos, Texas.

Using Webb's Mid-Infrared Instrument (MIRI), scientists studied two compact and two extended disks around Sun-like stars. While compact disks are expected to experience efficient pebble drift, delivering pebbles to well within a distance equivalent to Neptune's orbit, the extended disks are expected to have their pebbles retained in multiple rings as far out as six times the orbit of Neptune, according to NASA's post.

Scientists used Webb's high resolving power to determine whether compact disks have a higher water abundance in their inner, rocky planet region. The team leveraged the unprecedented resolving power of MIRI's MRS (the Medium-Resolution Spectrometer) which is sensitive to water vapor in disks.

As expected, the findings revealed excess cool water in the compact disks, compared with the large disks.

"Now we finally see unambiguously that it is the colder water that has an excess. This is unprecedented and entirely due to Webb’s higher resolving power," said Banzatti.

Their findings are published in the November 8 edition of the Astrophysical Journal Letters.

A breakthrough discovery!Baby stars are surrounded by disks of material. Scientists theorized that icy pebbles drift from the outer to the inner regions of a disk, delivering water & solids that form planets. New data from Webb shows this in action: https://t.co/bQ17PbYIAL pic.twitter.com/0lQpjeMMgm

— NASA Webb Telescope (@NASAWebb) November 8, 2023