Thanks to the James Webb Telescope (JWST), astronomers have obtained crucial evidence for the existence of crystalline water ice in another star system. This discovery allows us to study how it affects the processes that lead to the formation of planets.
Water ice is a vital component of protoplanetary disks. It has a major influence on the formation of giant planets, and can also be delivered by small bodies such as comets and asteroids to fully formed rocky planets.
However, despite the mass of circumstantial evidence, until recently astronomers had no direct evidence that frozen water is scattered around other stars. That has changed thanks to JWST. It was able to confirm the presence of crystalline water ice in the clastic disk around the young sun-like star HD 181327. It is located 155 light-years away from Earth and is only 23 million years old.
The debris disk around HD 181327 is analogous to the Kuiper belt as it looked billions of years ago. The disk is made up of dwarf planets, comets, and smaller rock and ice objects that sometimes collide with each other. This results in the emission of ice particles that are ideal for JWST observations.
According to the researchers, JWST found not just water ice, but crystalline water ice similar to that which makes up Saturn’s rings and Kuiper belt objects. It is combined with fine dust particles scattered throughout the disk, forming many small “dirty snowballs”. JWST observations also revealed the presence of a wide region completely free of dust between the star and its debris disk.
Water ice is distributed unevenly throughout the HD 181327 system. Most of it is located at a large distance from the star, where it is coldest. The outer region of the clastic disk is more than 20% water ice. Closer to the center, its concentration decreases to 8%. This may be because the star’s ultraviolet radiation vaporizes nearby water ice particles. It is also possible that some of the water is “locked” in the interior of planetesimals (embryos of future planets).
The discovery of JWST is a very important step towards understanding how planets form. In the future, researchers intend to continue studying protoplanetary disks to get more information about the processes occurring in them.
You can also read about James Webb’s study of Titan’s atmosphere.
According to NASA
