Astronomers have discovered the largest sulfur-containing molecule ever seen in space, offering new clues about how the chemical ingredients of life may form long before planets and stars are born.
The molecule, known as 2,5-cyclohexadiene-1-thione (C₆H₆S), was identified by researchers from the Max Planck Institute for Extraterrestrial Physics in collaboration with scientists from Spain’s Centro de Astrobiología.
The molecule was found in a massive cloud of gas and dust called G+0.693–0.027, located near the center of the Milky Way about 27,000 light-years from Earth.
This region has not yet formed stars, making the discovery especially striking. The results were published in the journal Nature Astronomy.
What makes this molecule remarkable is its size and structure.
It contains 13 atoms arranged in a stable six-membered ring, making it far larger and more complex than any sulfur-bearing molecule previously detected in interstellar space.
Until now, astronomers had only identified much smaller sulfur compounds, usually with six atoms or fewer.
Sulfur is a key element for life on Earth. It plays an essential role in proteins and enzymes, helping cells function properly. Scientists have long suspected that complex sulfur-containing molecules should exist in space, especially since similar compounds are found in meteorites and comets. However, direct evidence of such molecules forming in the interstellar medium had been missing.
“This is the first clear detection of a complex, ring-shaped sulfur molecule in space,” said Mitsunori Araki, lead author of the study. “It helps close a long-standing gap between the chemistry we see in space and the organic material found in our solar system.”
To make the discovery, the team combined laboratory work with astronomical observations. In the lab, they created the molecule by applying a powerful electrical discharge to thiophenol, a sulfur-rich liquid known for its strong odor.
Using a specially designed spectrometer, they measured the precise radio frequencies emitted by the molecule. These frequencies act like a fingerprint, allowing scientists to recognize the molecule when they see the same signals in space.
The researchers then compared this laboratory fingerprint with data from large radio telescope surveys conducted in Spain using the IRAM 30-meter and Yebes 40-meter telescopes. The match was unmistakable.
“This shows that a fairly large and complex molecule already exists in a cold, starless cloud,” said Valerio Lattanzi, a co-author of the study. “It means the chemical foundations for life are being laid much earlier than we once thought.”
The discovery suggests that many more complex sulfur-based molecules may be waiting to be found. It also strengthens the idea that the building blocks of life did not originate solely on planets like Earth, but were assembled in deep space and later delivered to young worlds by comets and asteroids.
Source: KSR.
