JWST’s unprecedented ability to peer into the shrouded hearts of distant clouds has revealed the elements of biochemistry in the coldest and darkest place we’ve seen them yet.
In a molecular cloud called Chamaeleon I, located more than 500 light-years from Earth, data from the telescope has revealed the presence of frozen carbon, hydrogen, oxygen, nitrogen and sulfur – elements that are essential for the formation of atmospheres and molecules such as amino. acids, collectively known as CHONS.
“These elements are important components of prebiotic molecules such as simple amino acids – and thus life ingredients, so to speak,” says astronomer Maria Drozdovskaya at the University of Bern in Germany.
In addition, an international team of researchers led by astronomer Melissa McClure from Leiden University in the Netherlands has also identified frozen forms of more complex molecules, such as water, methane, ammonia, carbonyl sulphide and the organic molecule methanol.
Cold, dense clumps in molecular clouds are where stars and their planets are born. Scientists believe CHONS and other molecules were present in the molecular cloud that gave birth to the Sun, some of which were later delivered to Earth via icy comet and asteroid collisions.
Although the elements and molecules discovered in Chamaeleon I are floating around quietly right now, they could one day be caught up in planet formation, providing the ingredients necessary for the emergence of life on new baby planets.
“Our identification of complex organic molecules, such as methanol and potentially ethanol, also suggests that the many star and planetary systems developing in this particular cloud will inherit molecules in a fairly advanced chemical state,” explains astronomer Will Rocha at the Leiden Observatory.
“This may mean that the presence of prebiotic molecules in planetary systems is a common result of star formation rather than a unique feature of our own solar system.”
Chamaeleon I is cold and dense, a dark conglomeration of dust and ice that forms one of the closest active star-forming regions to Earth. A census of the composition can therefore tell us a lot about the ingredients that go into star and planet formation and contribute to an understanding of how these ingredients are incorporated into newly forming worlds.
JWST, with its powerful infrared detection capabilities, is able to see through dense dust with more clarity and detail than any telescope that has come before. That’s because infrared wavelengths of light don’t scatter dust particles the way shorter wavelengths do, meaning that instruments like JWST can effectively see through dust better than optical instruments like Hubble’s.
To determine the chemical composition of the dust in Chamaeleon I, scientists rely on absorption signatures. Starlight traveling through the cloud can be absorbed by elements and molecules within it. Different chemicals absorb different wavelengths. When a spectrum of the emerging light is collected, these absorbed wavelengths are darker. Scientists can then analyze these absorption lines to determine which elements are present.
JWST peered deeper into Chamaeleon I for a census of its composition than we’ve ever seen before. It found silicate dust grains, the aforementioned CHONS and other molecules, and ice colder than any previously measured in space, around -263 degrees Celsius (-441 degrees Fahrenheit).
And they found that for the density of the cloud, the amount of CHONS was lower than expected, including only about 1 percent of the expected sulfur. This suggests that the rest of the materials may be locked up in places that cannot be measured – for example inside rocks and other minerals.
Without more information it is difficult to measure at this point, so more information is what the team intends to get. They hope to get more observations that will help them chart the evolution of these ices, from coating the dusty grains in a molecular cloud to their incorporation into comets and perhaps even to the seeding of planets.
“This is just the first in a series of spectral snapshots that we will get to see how the ices evolve from their initial synthesis to the comet-forming regions of protoplanetary discs,” says McClure.
“This will tell us what mix of ices – and therefore what elements – may eventually be delivered to the surfaces of terrestrial exoplanets or incorporated into the atmospheres of giant gas or ice planets.”
The research is published in Natural astronomy.
And you can download wallpaper-sized versions of JWST’s image of Chamaeleon I here.