Before stars, planets, and moons, there is just a big collection of dust and gas known as a molecular cloud. These vast interstellar realms give rise to new stars as the gas collapses under gravity. But before that, they’re intensely frigid and hard to observe due to their density. However, the James Webb Space Telescope was built for this, and an international team of astronomers just used it to peer inside the Chamaeleon I cloud. It found numerous types of ice at the lowest temperatures ever recorded.
Chamaeleon I is a star-forming region about 500 light-years away from Earth (see above). The region of the cloud observed by Webb is known for being isolated from current star formation and extremely dense. That makes it incredibly cold, too. So, we’re not just talking about water ice, but ice based on all manner of frozen molecules. Webb’s incredible sensitivity in infrared allowed it to capture absorption spectra as starlight passed through the cloud, making it possible to identify elements that are key to the development of terrestrial planets: carbon, hydrogen, oxygen, nitrogen, and sulfur (known collectively as CHONS).
A statement from the University of Bern notes that the ice discovered in Chamaeleon I has set a record as the coldest ever. Webb measured these specs of ice at a staggering -263 degrees Celsius (-441 degrees Fahrenheit). That’s just 10 degrees Celsius above absolute zero. More important than the temperature of the ice is what it’s made of. Webb detected all the CHONS ingredients in forms like carbonyl sulfide, ammonia, and methane. “We simply couldn’t have observed these ices without Webb,” says Webb project scientist Klaus Pontoppidan.
The cloud even contained a trace of methanol, the simplest complex organic molecule. When combined with other icy molecules, methanol can form amino acids, which are the basic building blocks of proteins. Scientists believe that many of these essential compounds for life were seeded on Earth by comet and asteroid impacts. The latest Webb observations suggest these materials were already forming in the cold molecular cloud that would give rise to our solar system.
Using Webb’s observations of Chamaeleon I, astronomers were able, for the first time, to estimate the amount of sulfur in pre-stellar ice. While the levels are higher than previous measurements, they’re lower overall than the team expected. It’s the same for all the other CHONS elements. This presents a challenge for astronomers to determine where the materials are hiding — for example, inside soot-like materials or rocks that won’t appear in Webb’s absorbance spectra.
The research is part of the Ice Age Project, one of the early-release science programs undertaken by Webb. The team is already planning follow-up observations that may be able to trace the journey of ice from the molecular cloud state all the way to the formation of icy comets around a new solar system.
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