JWST reveals young star that may be about to give birth to a planet

Spectral information from the James Webb Space Telescope has unveiled chemicals inside a protostar that hint it is in the process of forming planets.

A young, still-forming star that produces so-called complex carbon molecules like ethanol and acetaldehyde has been glimpsed by the James Webb Space Telescope (JWST). The compounds it is making could be the building blocks of future planets.

Such protostars consist of large volumes of gas, or gas and ice, that slowly coalesce into stars under the pull of gravity. Complex carbon molecules, which can act as building blocks for life, have been observed in some protostar gas clouds, but a lack of detailed data means we can’t tell exactly which compounds form, and whether they are formed in ice.

Now, Klaus Pontoppidan at the Space Telescope Science Institute in Maryland and his colleagues have measured the infrared light coming from an icy protostar, IRAS 15398-3359, in high detail for the first time using JWST’s Mid-Infrared Instrument. As well as observing strong signals of water ice in the spectrum of light from the star, Pontoppidan and his team have spotted spectral characteristics typically associated with molecules that contain carbon.

“This is the first time we have had the precision in the data to tease out these very weak features,” says Pontoppidan. “We’ve seen things like methanol, the simplest alcohol, before, but now we think we may see more complex things like ethanol, for example, in the spectrum.”

To fully confirm what they are seeing, the researchers will need to do laboratory experiments that show the same mix of compounds produce spectra which match JWST’s observations. If so, Pontoppidan and his colleagues are hopeful that this will help our understanding of how the molecules for planets and life were created. “If we do confirm that we see [ethanol], and in the amounts that we think, then it’ll be a surprise for us. It seems like the ice is more chemically complex than we initially thought,” says Pontoppidan.

As well as spotting carbon in the spectrum of light, the researchers saw a signature that might be water vapour at around a few hundred degrees kelvin (-73 to 26°C or -100 to 80°F), which could be a sign that a disc of matter around the protostar that will eventually coalesce into planets is forming, says Pontoppidan.

“The physical data we’re seeing now from JWST is of a quality that we can easily get in the laboratory,” says Martin McCoustra at Heriot-Watt University in Edinburgh, UK. “So now it becomes much easier to make comparisons between laboratory data and space observational data in a way that’s useful for helping us to identify chemical compounds.”


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