by Scientists utilizing NASA’s James Webb Space Telescope have unveiled a groundbreaking discovery that sheds light on the formation of planets. Through the observation of water vapor in protoplanetary disks, the Webb telescope has confirmed the existence of a physical process involving the movement of ice-coated solids from the outer regions of the disk to the zone where rocky planets are formed.
The concept that icy pebbles, which form in the cold outer regions of protoplanetary disks (the same area where comets originate in our solar system), serve as the fundamental building blocks of planet formation has long been theorized.
According to these theories, pebbles should drift inward toward the star due to friction within the gaseous disk, delivering solid materials and water to planets.
One of the fundamental predictions of this theory is that as icy pebbles enter the warmer region within the snowline, where ice transitions to vapor, they should release significant amounts of cold water vapor.
And that is precisely what the Webb telescope has observed.
According to the principal investigator, Andrea Banzatti of Texas State University, San Marcos, Texas, the Webb telescope has finally provided evidence of the connection between water vapor in the inner disk and the drift of icy pebbles from the outer disk.
This discovery presents exciting opportunities for further research on the formation of rocky planets using the Webb telescope.
Previously, scientists had a rather static understanding of planet formation, envisioning isolated zones where planets would form. However, this recent finding demonstrates that these zones can interact with each other. It also supports the hypothesis that similar processes may have occurred in our own solar system.
To conduct their research, the team utilized Webb’s Mid-Infrared Instrument (MIRI) to study four protoplanetary disks, two of which were compact and the other two extended. These disks orbited stars similar to our Sun and were estimated to be between 2 and 3 million years old.
The compact disks were expected to undergo efficient pebble drift, bringing pebbles close to the distance of Neptune’s orbit. In contrast, the extended disks were anticipated to retain their pebbles in multiple rings as far out as six times the orbit of Neptune.
The Webb telescope’s observations aimed to determine whether compact disks had a higher water abundance in their inner, rocky planet region, as predicted by the more efficient pebble drift hypothesis. To study water vapor in the disks, the researchers employed MIRI’s Medium-Resolution Spectrometer (MRS), which proved to be sensitive to water vapor.
The results of the study confirmed the team’s expectations by revealing an excess of cool water in the compact disks compared to the larger disks.
As the pebbles drift, whenever they encounter a pressure bump, they tend to collect in that area. These pressure traps do not necessarily impede pebble drift, but they certainly hinder it. This is precisely what appears to be occurring in the larger disks with rings and gaps.
According to current research, large planets may create rings of increased pressure where pebbles accumulate. It is believed that Jupiter may have played a similar role in our own solar system by inhibiting the delivery of pebbles and water to our small, inner, and relatively water-poor rocky planets.
When the data first emerged, the results perplexed the researchers. For two months, they were puzzled by the preliminary findings indicating that the compact disks contained colder water, while the larger disks had overall hotter water. This discrepancy seemed incomprehensible since the team had specifically chosen stars with very similar temperatures.
Only after overlaying the data from the compact disks onto the data from the larger disks did the answer become clear. The compact disks featured extra cool water just inside the snowline, at a distance roughly ten times closer than the orbit of Neptune.
According to Banzatti, “Now we finally see unambiguously that it is the colder water that has an excess.” This unprecedented finding is entirely due to the Webb telescope’s higher resolving power.
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1. Source: Coherent Market Insights, Public sources, Desk research
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