Scientists have identified the largest organic molecule containing sulfur ever found in interstellar space.
This discovery is considered a "missing link" in understanding the cosmic origins of life's chemistry.
Sulfur is the tenth most abundant element in the universe and a critical component of amino acids, proteins, and enzymes on Earth. While researchers had previously detected sulfur-bearing molecules in comets and meteorites, there was a notable lack of large sulfur-containing molecules in interstellar space—the regions of dust and gas between stars.
A Landmark Sulfur Discovery
Mitsunori Araki, lead author of the study published in Nature Astronomy, noted that while sulfur should be abundant, finding sulfur-bearing molecules in space has been challenging. The new detection, a molecule named 2,5-cyclohexadiene-1-thione, comprises 13 atoms, making it the largest sulfur-bearing molecule yet observed in space. Previous detections typically involved molecules with only three to five atoms.
This finding helps to bridge the gap between the simple chemistry observed in space and the more complex building blocks of life found in comets and meteorites. The discovery suggests that more, potentially larger, sulfur-containing molecules could be detected in the future.
Where and How it Was Found
The molecule was found within G+0.693–0.027, a molecular cloud located approximately 27,000 light-years from Earth near the center of our galaxy. Molecular clouds are dense concentrations of dust and gas where molecules form and stars are born. Valerio Lattanzi, a co-author, explained that the ingredients embedded in these clouds are eventually transferred to forming planetary systems.
Researchers synthesized the molecule by applying an electric discharge to thiophenol, a substance containing sulfur, carbon, and hydrogen. They then obtained a precise "radio fingerprint" which was compared with existing telescope data from the IRAM-30m and Yebes radio telescopes in Spain.
Expert Perspectives on Significance
Experts not involved in the study commented on its significance. Kate Freeman, a geosciences professor at Penn State University, stated that the study contributes to understanding how complex sulfur compounds found in meteorites originated.
Sara Russell, a planetary sciences professor at the Natural History Museum in London, suggested that the presence of complex organic molecules in the Milky Way's center implies that biologically important materials may be widespread, increasing the likelihood of life existing elsewhere.
Ryan Fortenberry, a chemistry professor at the University of Mississippi, highlighted sulfur's unique chemistry and its role in understanding where life could have started and evolved.