For the first time, astronomers have identified key organic compounds essential for life in frozen form outside the Milky Way. A research team led by Marta Sewiło of NASA and the University of Maryland discovered a range of complex organic molecules, including ethanol, acetaldehyde, and methyl formate, encased in ice orbiting a newborn star located in the Large Magellanic Cloud. This groundbreaking finding suggests that the ingredients necessary for the emergence of life are not confined to our galaxy.
The team made this discovery while studying a young star designated ST6, situated approximately 160,000 light-years from Earth within a superbubble known as N158, near the well-known Tarantula Nebula. The presence of these molecules in ice form marks a significant achievement, as the identified compounds had not previously been observed frozen in space outside our galaxy. Notably, acetic acid was detected in solid form for the first time, having only been found in vapor previously.
Significance of the Findings
Complex organic molecules (COMs) are defined as having at least six atoms, with at least one carbon atom. They include a variety of compounds critical to the formation of life, such as amino acids and sugars. The detection of these molecules in the Large Magellanic Cloud indicates that the conditions necessary for prebiotic chemistry may exist widely across the universe, extending beyond the Milky Way.
Sewiło emphasized the importance of this research, stating, “With this discovery, we’ve made significant advancements in understanding how complex chemistry emerges in the Universe, opening new possibilities for research into how life came to be.” The findings provide crucial insights into the origins of prebiotic chemistry and the environments where these foundational compounds may have formed before Earth was created.
The Large Magellanic Cloud presents a unique environment compared to the Milky Way, with only about a third to half of the heavy metal abundance found in our galaxy. This means it contains lower levels of elements like oxygen, carbon, and silicon, as well as significantly less dust to obstruct light. Additionally, the intense star formation in the LMC generates substantial ultraviolet radiation, raising questions about how COMs can form in such conditions.
Research Methodology and Future Directions
To investigate the chemistry surrounding ST6, Sewiło and her team utilized the James Webb Space Telescope (JWST), focusing on mid-infrared light emitted by the icy material surrounding the star. They compared the obtained spectra to a known database of COM signatures, allowing for the identification of methanol, acetaldehyde, ethanol, methyl formate, and acetic acid.
The presence of these molecules supports existing models and laboratory experiments that propose acetic acid participates in grain-surface reactions that contribute to the formation of prebiotic compounds in space. The researchers suggest that these molecules are likely products formed through grain-surface chemistry, where ice forms on dust grains and facilitates reactions that create COMs.
The team plans to expand their research to additional young stars within the Large Magellanic Cloud, aiming to determine if similar chemistry occurs throughout the entire dwarf galaxy or if ST6 is an anomaly. Sewiło noted, “We currently only have one source in the Large Magellanic Cloud and only four sources with detection of these complex organic molecules in ices in the Milky Way. We need larger samples from both to confirm our initial results that indicate differences in COM abundances between these two galaxies.”
This research has been published in The Astrophysical Journal Letters, marking a significant step forward in our understanding of the cosmic origins of life’s building blocks. As scientists continue to explore the universe, the implications of these findings may reshape our understanding of where and how life can emerge beyond Earth.
