New Webb Telescope Research Sheds Light on Rocky Planet Formation

Rebecca Jean T.
6 min readFeb 29, 2024

In November of 2023, two separate research endeavors using the James Webb Space Telescope peered into the planet-forming disks surrounding protostars in our galaxy to learn more about how planets are created. Both papers have found new information on how rocky planets are formed, increasing our understanding of planetary evolution and the types of conditions in which rocky worlds can form.

Concept art of reddish purple protoplanetary disk around a white star. A red planet is located in the upper right corner.
Concept art of star PDS 70 and its protoplanetary disk. Water vapor has been detected in the inner part of the disk, where rocky planets may be forming. The illustration also features one of two known protoplanets currently in the disk. Credit: NASA, ESA, CSA, J. Olmsted (STScI).

Confirming Theories of Planetary Formation

In a paper published in the Astrophysical Journal Letters on November 8th, astrophysicists using the James Webb Space Telescope found evidence confirming theories about how planet formation works. Current theories suggest that planets form in disks of material that surround newborn stars, known as protoplanetary disks. During this stage of stellar evolution, known as the T Tauri phase, these developing stars eject hot winds into space around them. This energy disturbs the material around the star, causing small bits to stick together and form larger and larger debris. Once enough debris has been gathered together, it becomes a planetesimal.

Theories of planet formation have also proposed that icy pebbles far in the outer regions of protoplanetary disks are essential in planet formation. These icy pebbles are responsible for bringing both solid material and water to planets throughout a planetary system as they drift inwards toward the star due to friction in the material of the protoplanetary disk. Specifically, it is thought that these icy pebbles eventually enter a warmer region around the star, where they release cold water vapor.

Two concept images of protoplanetary disks. On the left: a compact red disks in the middle of the frame. On the right: a larger disk takes up the entire image, with gaps in material in circles in the disk. Both are red and orange.
Artist concept comparing two common types of protoplanetary disks. On the left, a compact disk. On the right, an extended disk with gaps in its material. Credit: NASA, ESA, CSA, Joseph Olmsted (STScI).

“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!” — principal investigator Andrea Banzatti of Texas State University.

The newly published research shows exactly what theories suggest. Using Webb’s MIRI (Mid-Infrared Instrument), the team studied four protoplanetary disks. Two were compact disks, and…

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Rebecca Jean T.

Published author on NASA’s Radio Jove project. Researching science topics to deliver to you in bite-sized stories.