Astronomers may have finally solved a long-standing cosmic mystery: how minerals that require extreme heat end up inside comets formed in the coldest reaches of planetary systems.
New observations from NASAโs James Webb Space Telescope show that crystalline silicatesโminerals forged only at very high temperaturesโare created near young stars and then flung outward to distant, frigid regions where comets are believed to form.
The findings, published on 18 June in Nature, offer the clearest evidence yet of how these minerals travel from hot inner disks to icy outer zones, a process long suspected but never directly observed.
From fire to ice
Crystalline silicates have been found in comets in our own solar system, despite those comets spending most of their lives in deep-freeze regions like the Kuiper Belt and the Oort Cloud. Scientists have struggled to explain how such heat-formed materials reached places so far from the Sun.
By studying a young, actively forming star known as EC 53, Webb provided a crucial missing link.
The telescope revealed that crystalline silicates form close to the star, in the hottest inner part of its disk of gas and dustโroughly equivalent to the region between the Sun and Earth in our solar system. More importantly, Webb also detected powerful winds and outflows capable of carrying these newly formed crystals outward to the colder edges of the disk.
โThese layered outflows appear to lift crystalline silicates and transport them outward, like a cosmic highway,โ said lead author Jeong-Eun Lee of Seoul National University.
A predictable young star
EC 53, located about 1,300 light-years away in the Serpens Nebula, is unusual among young stars because its activity follows a regular pattern. About every 18 months, it enters a dramatic 100-day outburst, rapidly consuming gas and dust from its surrounding disk.
During these bursts, the star ejects part of that material as jets and windsโsome of which, scientists say, likely carry crystalline silicates toward the outer regions where comets may eventually take shape.
Using Webbโs Mid-Infrared Instrument (MIRI), researchers identified specific minerals near the star, including forsterite and enstatiteโboth common on Earth. They also mapped where these minerals are located during calm periods and during explosive outbursts.
โSilicates are the main building blocks of rocky planets like Earth,โ said co-author Doug Johnstone of the National Research Council of Canada. โSeeing these same minerals forming and moving through another planetary system is extraordinary.โ
How planets may form
The new data help explain why crystalline silicates have been detected not only in comets but also in disks around other stars. Until now, scientists lacked direct proof of how the minerals were transported across vast distances.
Webb also captured detailed views of EC 53โs high-speed jets of hot gas and slower, cooler outflows rising from the diskโkey mechanisms believed to redistribute material across the system.
โItโs not just what Webb can see, but where it sees it,โ said Joel Green, an instrument scientist at the Space Telescope Science Institute. โWe can now track how these tiny particlesโmuch smaller than grains of sandโare created and spread throughout a young star system.โ
A glimpse of our own past
EC 53 is still deeply embedded in dust and may remain so for another 100,000 years. Over millions of years, repeated collisions among dust and pebbles in its disk could gradually build larger bodies, eventually forming planets.
Scientists believe this process mirrors what happened in our own solar system billions of years agoโleaving behind planets, comets, and a system โlitteredโ with crystalline silicates.
The James Webb Space Telescope, led by NASA in partnership with the European Space Agency and the Canadian Space Agency, continues to transform scientistsโ understanding of how stars and planetary systems formโand how the ingredients for worlds like our own are distributed across the cosmos.
Image: NASA, ESA, CSA, STScI, Klaus Pontoppidan (NASA-JPL), Joel Green (STScI); Image Processing: Alyssa Pagan (STScI)
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