In a significant breakthrough for astrobiology, astronomers have identified complex organic molecules in ice surrounding a young star named ST6, located in the Large Magellanic Cloud, a galaxy approximately 160,000 light-years from Earth. This discovery, made using the James Webb Space Telescope’s (JWST) Mid-Infrared Instrument (MIRI), sheds light on how the chemical ingredients necessary for life could disseminate across the universe. The findings were detailed in a study published in the Astrophysical Journal Letters on October 20, 2025.
The research team, led by Marta Sewilo from the University of Maryland and NASA, detected five different carbon-based compounds in the ice surrounding the protostar. These include methanol and ethanol, both common alcohols, as well as methyl formate, acetaldehyde, and acetic acid, the latter of which has never before been conclusively found in space ice. The presence of ethanol, methyl formate, and acetaldehyde marks the first time these complex organic molecules (COMs) have been detected in ice outside the Milky Way galaxy.
Another intriguing observation was the potential detection of glycolaldehyde, a sugar-related molecule that could serve as a precursor to complex biomolecules such as components of RNA. However, further studies are required to confirm this finding. “It’s all thanks to JWST’s exceptional sensitivity combined with high angular resolution that we’re able to detect these faint spectral features associated with ices around such a distant protostar,” Sewilo explained.
Insights into Cosmic Chemistry
What makes this discovery particularly compelling is the environment in which these molecules were found. The Large Magellanic Cloud, with its lower metallicity—indicating a reduced abundance of elements heavier than hydrogen and helium—serves as a natural laboratory for studying star formation under conditions reminiscent of the early universe. The galaxy contains about one-third to one-half the heavy elements found in our solar system and experiences significantly stronger ultraviolet radiation.
“The low metallicity environment is interesting because it’s similar to galaxies at earlier cosmological epochs,” Sewilo elaborated. “What we learn in the Large Magellanic Cloud can help us understand more distant galaxies from when the universe was much younger. The harsh conditions provide insights into how complex organic chemistry can occur where fewer heavy elements are available for reactions.”
Study co-author Will Rocha from Leiden University pointed out that COMs can form both in gas and in ices on interstellar dust grains. After their formation, these icy compounds can be released into gas phases. Previous detections of methanol and methyl formate were made in the gas phase in the Large Magellanic Cloud.
Despite the formation process of these molecules still being somewhat elusive, chemical models and laboratory experiments indicate that reactions occurring on the surfaces of interstellar dust grains significantly contribute to COM production. “Our detection of COMs in ices supports these results,” Rocha stated. “It provides evidence that these reactions can effectively produce COMs even in harsher environments than those found in the solar neighborhood.”
The presence of icy COMs under conditions similar to those in the early universe suggests that the building blocks for larger biomolecules essential for life may have formed much earlier and under a broader variety of cosmic circumstances than previously believed. Although these findings do not confirm the existence of life beyond Earth, they imply that these organic molecules could survive the formation of planetary systems and potentially contribute to conditions suitable for life on early planets.
Future Research Directions
Sewilo plans to extend this research to include additional protostars in both the Large Magellanic Cloud and the Small Magellanic Cloud, the next closest galaxy to Earth. “Currently, we only have one source in the Large Magellanic Cloud with complex organic molecules detected in ices, and just four sources in the Milky Way,” she noted. “We need larger samples from both to confirm our initial results, which suggest differences in COM abundances between these two galaxies.”
With this groundbreaking discovery, the team has made significant strides in understanding how complex chemistry emerges in the universe, opening new avenues for research into the origins of life. The study was supported by NASA and highlights the importance of continued exploration in astrobiology and astrochemistry.
