Water Vapor Found in Zone Conducive to Rocky Planet Formation

An artist’s concept of the protoplanetary disk surrounding PDS 70. Credit: NASA, ESA, CSA, J. Olmsted (STScI).

The search for extraterrestrial life and habitable planets revolves around the search for water since water is essential to all forms of life. One place to look for water is in solar systems just forming. When a star is born, dispersed gas and dust coalesce and eventually condense into protoplanetary disks. Commonly, two distinct disks form: an inner disk and an outer disk. The inner disk is where rocky planets, like Earth, form and is usually dominated by high-melting-point materials, such as silicate. The outer disk is dominated by lower-melting-point materials, such as water.  

Giulia Perotti from the Max Planck Institute for Astronomy in Heidelberg, Germany, and her team used JWST’s Mid-Infrared Instrument (MIRI) to detect water vapor in the inner disk of a protoplanetary disk. The star PSD 70 is a K-type star and is estimated to be 5.4 million years old. This is relatively old for stars with planet-forming disks, which makes the discovery of water vapor even more exciting. The water vapor was found less than 100 million miles from the star, which leads to questions about how this is possible. The star’s radiation and winds should have blown the water vapor out of the inner disk if the radiation hadn’t broken down the water molecules first. This is the first time water vapor has been detected in the terrestrial region of a disk known to host two or more protoplanets (PSD 70 has two gas giants in its outer disk). While rocky planets were not discovered, their building blocks were. These building blocks could be seeded with water vapor which might lead to the development of a habitable world. Future studies using JSWT instruments could glean new insights into how water vapor survived this long within an inner disk. READ MORE