JWST Sees Organic Molecules Swirling Around a Newborn Star

One of the most interesting questions we can ask is, “How did life form?”. To answer it, scientists go back to look at the basic chemical building blocks of life. Those are water, carbon-based organic molecules, silicates, and others. The James Webb Space Telescope offered a peek at the gases, ice particles, and dust surrounding a newborn star and found organic molecules exist there.

The data from Webb is set to transform our understanding of the chemistry of newly formed stars. That’s because the telescope can detect the existence of organic molecules around the protostar MIRI 15398-3359. It’s forming in the Lupus 1 molecular cloud (also known as B228), some 500 light-years away from us. The telescope has found absorption features indicating the existence of water, methanol, ammonia, and methane ices. There also appear to be species of ethanol and acetaldehyde, in addition to carbon monoxide and water vapor. These are all complex organic molecules that can combine to form the building blocks of life.

Using Other Molecules to Track Stellar Activity

Since this is a newborn protostar, it’s showing some jet activity as well. Webb found emission lines from species of iron, neon, silicon, and hydrogen gas. These all trace a bipolar jet moving away from the stormy young star. MIRI 15398-3359, like many others, is still feeding on the envelope of material that created it. The cloud of gas and dust that formed its creche is chemically active.

Essentially, it’s taking simple building blocks and churning out those complex organic molecules. They’re precursors to the chemicals of life—existing long before conditions on any nearby worlds have even formed. This is not the first time astronomers have the raw materials for life’s chemicals in stellar nurseries. Other clouds of gas and dust seem to show these complex chemicals, too. But, Webb’s exquisite data show more details about what’s going on in the cloud.

A false-color image obtained by the James Webb Space Telescope (JWST) of a protostar (orange region in upper left; a different protostar from the one in the present study). JWST uses infrared instruments to study how protostars shape the chemistry of icy clouds (blue wisps). Courtesy: NASA, ESA, CSA

Forming Organic Molecules

A research team at the Japanese research institution RIKEN analyzed the Webb data from this newly forming star. They concluded that these complex organic molecules are forming on the surfaces of ice grains in the cloud of gas and dust. As the star warms those molecules, they migrate away from their icy homes and swirl into the cloud.

“We want to obtain definitive proof of such formation pathways,” said Yao-Lun Yang of the RIKEN Star and Planet Formation Laboratory. “And JWST provides the best opportunity to do so.”

To understand what’s happening at the star, Yang and the team used data from observations of the star made by Webb’s Mid-Infrared Instrument (MIRI) in 2022. It wasn’t the first time telescopes had looked at MIRI 15398-3359. Previous observations had found some of these chemicals in the gas phase—well after they’d formed. The MIRI observations dug more deeply into the cloud to identify these species in their ice phase.

An Early Peek at a Baby Star

The process of star birth has long been veiled by the clouds where those chemicals exist. Specialized instruments such as MIRI look more deeply into the clouds. It offers a view of chemical evolution much earlier in the process of star formation. The observations also allowed astronomers to put a tentative time frame on the existence of the jets and outflows from this baby star. According to Yang, the ejections are perhaps only 170 years old. That’s incredibly early in the process. But, it does give astronomers a good idea of just how soon a newborn star becomes active. The observation of complex organic chemicals in the cloud in both gas and ice form also tells scientists more about the chemical evolution that takes place in stellar creches.

As the star progresses in its evolution, and possible planets form in the protoplanetary disk around MIRI 15398-3359, Webb should be able to continue peeking inside its birthplace. Tracing the formation of life on those planets will require scientists to track the continued evolution of those complex organic molecules from gas clouds to a planetary surface. It’s a very promising breakthrough in understanding the long road from star formation to life. “We will begin to understand how organic chemistry emerges,” said Yang. “And we will also uncover the lasting impacts on planetary systems similar to our Solar System.”

For More Information

Space Telescope Probes Chemistry Around a Newborn Star
CORINOS. I. JWST/MIRI Spectroscopy and Imaging of a Class 0 Protostar IRAS 15398–3359

Carolyn Collins Petersen

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