Largest sulfur-containing molecular compound discovered in space
For the first time, a complex ring-shaped molecule with 13 atoms has been discovered in interstellar space based on laboratory studies. The discovery combines simple chemistry in space with the complex organic building blocks found in comets and meteorites. This could be a crucial step toward explaining the cosmic origins of the chemistry of life.
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At the heart of our galaxy, scientists discovered the first sulfur-containing six-membered ring molecule hidden in an interstellar cloud. [Großansicht] |
Scientists from the Max Planck Institute for Extraterrestrial Physics (MPE), in collaboration with astrophysicists from the Astrobiology Center (CAB), CSIC-INTA, has identified the largest sulfur-containing molecule in interstellar space to date: 2,5-cyclohexadiene-1-thione (C₆H₆S). This breakthrough was achieved by combining laboratory experiments and astronomical observations. The molecule is located in the G+0.693-0.027 molecular cloud, about 27,000 light-years from Earth near the center of the Milky Way. With a stable six-membered ring and a total of 13 atoms, it significantly exceeds the size of all sulfur-containing compounds previously detected in space.
“This is the first clear discovery of a complex, ring-shaped sulfur-containing molecule in interstellar space – and a crucial step in understanding the chemical connection between space and the building blocks of life,” said Dr. Mitsunori Araki, scientist at MPE. So far it has only been possible to detect small sulfur compounds – usually with six atoms or fewer – in interstellar space. Large, complex sulfur-containing molecules have long been expected due to the key role of sulfur in proteins and enzymes, but have remained undiscovered. This gap between interstellar chemistry and the organic inventory of comets and meteorites has been a central puzzle in astrochemistry.
The C₆H₆S that has now been discovered is structurally related to molecules that occur in extraterrestrial samples – and is the first of its kind to be clearly detected in space. It represents a direct chemical “bridge” between the interstellar medium and our solar system. The identification was based on a combination of laboratory work and subsequent astronomical observations. The team synthesized the molecule in the laboratory by applying a 1,000-volt electrical discharge to the foul-smelling liquid thiophenol (C₆H₅SH).
Using a self-developed spectrometer, the researchers precisely measured the radio wave frequencies of C₆H₆S and generated a unique radio fingerprint with more than seven significant decimal places. This signal was then compared with astronomical data from an extensive observation campaign led by the CAB, collected with the IRAM 30 m and Yebes 40 m radio telescopes in Spain.
“Our results show that a 13-atom molecule structurally similar to those found in comets already exists in a young, starless molecular cloud. This proves that the chemical basis for life emerges long before star formation,” said Dr. Valerio Lattanzi, scientist at MPE. The discovery suggests that many more complex sulfur-containing molecules remain undiscovered – and that the fundamental building blocks of life may have originated in the depths of interstellar space long before Earth existed.
The team reports on the results of the study in a specialist article published in the journal Nature Astronomy has appeared.
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