NASA’s James Webb Space Telescope has made an unprecedented discovery – water vapor in the planetary system PDS 70, situated 370 light-years away. This marks the first instance where water has been found in the terrestrial zone of a disk where at least two young planets reside. This revelation holds great significance as it could shed light on how vital elements for life arrive at rocky exoplanets, providing further insights into Earth’s own history.
The planetary system in question, PDS 70, houses two gas-giant planets within its complex structure of inner and outer disks of gas and dust. The disks are separated by a colossal gap spanning 8 billion kilometers. Intriguingly, the presence of water vapor was detected less than 160 million kilometers from the star. This falls within the zone where we believe terrestrial planets, similar to our own Earth, are formed.
Giulia Perotti, lead author of the research from the Max Planck Institute for Astronomy (MPIA) in Heidelberg, Germany, expressed her excitement over this discovery. She stated, “Although water has been observed in other disks, it is the first time we have seen it so close to a star in a system where planets are actively forming. Such measurement wouldn’t have been possible without the Webb telescope.”
This discovery holds extra significance as it investigates the area where rocky, Earth-like planets are usually formed, added Thomas Henning, MPIA director and co-author of the paper.
PDS 70 is classified as a K-type star, cooler than our Sun, and estimated to be around 5.4 million years old. This is considered relatively old for a star with planet-forming disks, making the presence of water vapor unexpected. Over time, such disks typically lose their gas and dust content due to the central star’s radiation and winds or because the dust develops into larger objects that eventually form planets.
Astronomers have not yet discovered any planet formation within the inner disk of PDS 70, but they observe the potential building blocks of rocky worlds, silicates. The presence of water vapor indicates that any rocky planets forming in this region will have access to water from the outset.
This discovery leads to questions about the origin of the water. It could be that water molecules are being formed in situ as hydrogen and oxygen atoms merge. Alternatively, dust particles coated in ice could be migrating from the colder outer disk to the warmer inner disk, where the ice would then sublimate into vapor.
Future studies employing two additional Webb’s instruments, NIRCam (Near-Infrared Camera) and NIRSpec (Near-Infrared Spectrograph), will strive to deepen our understanding of the PDS 70 system. This research has been published in the journal Nature and forms part of the Guaranteed Time Observation program 1282.
The James Webb Space Telescope’s efforts continue to unravel the mysteries of our solar system and probe into the uncharted territories of far-flung worlds and cosmic structures, thus enhancing our understanding of the universe and our place in it.
