JWST’s unparalleled 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 over 500 light-years from Earth, data from the telescope has revealed the presence of frozen carbon, hydrogen, oxygen, nitrogen, and sulfur – elements vital to 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 ingredients of life, so to speak,” says astronomer Maria Drozdovskaya of the University of Bern in Germany.
In addition, an international team of researchers led by astronomer Melissa McClure of Leiden University in the Netherlands has also identified frozen forms of more complex molecules, such as water, methane, ammonia, carbonyl sulfide, and the organic molecule methanol.
Cold, dense clumps in molecular clouds are where stars and their planets are born. Scientists believe that CHONS and other molecules were present in the molecular cloud that birthed the Sun, some of which were later delivered to Earth via icy comet and asteroid impacts.
Although the elements and molecules detected in Chamaeleon I are quietly floating about right now, one day, they could be caught up in planet formation, delivering the ingredients necessary for the emergence of life to new baby planets.
“Our identification of complex organic molecules, like methanol and potentially ethanol, also suggests that the many star and planet systems developing in this particular cloud will inherit molecules in a fairly advanced chemical state,” explains astronomer Will Rocha of Leiden Observatory.
“This could 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 constitutes one of the nearest active star-forming regions to Earth. A census of its composition, therefore, can tell us quite a bit 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 off dust particles the way shorter wavelengths do, which means 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 therein. Different chemicals absorb different wavelengths. When a spectrum of the light that emerges 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 ices colder than any measured before in space, at 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 around 1 percent of the expected sulfur. This suggests that the rest of the materials may be locked up in places that can’t be measured – inside rocks and other minerals, for instance.
Without more information, it’s difficult to gauge at this point, so more information is what the team intends to get. They hope to obtain more observations that will help them map out the evolution of these ices, from coating the dusty grains of a molecular cloud to their incorporation into comets and perhaps even to seeding planets.
“This is just the first in a series of spectral snapshots that we will obtain to see how the ices evolve from their initial synthesis to the comet-forming regions of protoplanetary discs,” McClure says.
“This will tell us which mixture of ices – and therefore which elements – can eventually be delivered to the surfaces of terrestrial exoplanets or incorporated into the atmospheres of giant gas or ice planets.”
The research has been published in Nature Astronomy.
And you can download wallpaper-sized versions of JWST’s image of Chamaeleon I here.