2024-10-18 09:15:00
The largest molecules found so far in space have been detected. Specifically, these are two molecules composed of 21 atoms each and which have been located in the cold interstellar cloud TMC-1. The discovery opens new avenues for understanding the chemical complexity of the universe.
The research that led to this discovery was conducted by an international team led by the Superior Council of Scientific Research (CSIC) in Spain.
Located in the constellation of Taurus, about 500 light years away, the interstellar cloud TMC-1 (Taurus Molecular Cloud) is one of the closest to observe the formation of stars like the Sun. This new discovery, in which the 40-meter radio The National Geographic Institute (IGN) telescope at the Yebes Observatory (Guadalajara, Spain) was used, representing a further step forward in understanding the chemical composition of this star-forming region.
Researchers have identified two cyanide compounds (organic molecules containing cyanide groups in their structure) derived from the polycyclic aromatic hydrocarbon (PAH) acenaphthylene (C12H8). PAHs, whose structure is made up of rings of carbon and hydrogen, are found naturally in substances such as coal or petrol. It is believed that these molecules could be one of the pillars on which the extraterrestrial origin of life is based.
Careful analysis of the derived rotation constants (transitions between the rotational or spin energy levels of these molecules) allowed scientists to focus on molecules larger than naphthalene (composed of 10 carbon atoms and 8 hydrogen atoms). , but smaller than anthracene and phenanthrene (consisting of 14 carbon atoms and 10 hydrogen atoms respectively, fused into three benzene rings). The procedure they used, based on the detection of all rotational lines of these molecules, guarantees an unambiguous identification compared to other techniques that use statistical methods.
Artistic representation of the molecules present in space. (Image: IFF)
“These results support a scenario in which PAHs grow in cold clouds from fused carbon rings of five and six carbon atoms and not just six, as believed until now,” emphasizes José Cernicaro, CSIC researcher at the Institute of Fundamental Physics (IFF), dependent on the CSIC.
Quantum chemical calculations, the chemical synthesis of these molecules, as well as spectroscopic study in the laboratory, support the molecular identifications made by this team. “In the spectrum, the molecules seemed to respond to the frequencies of molecules with unpaired electrons, which we call radicals, but it was only in appearance, they were just camouflaged, which so far made their detection difficult,” says the IFF researcher.
These findings are part of the Quixote project, which aims to unravel the chemical complexity of a cold interstellar cloud and which has enabled the discovery of more than 90 molecular species over the past four years. One of the most important results of this collaboration was the discovery, using the standard line-by-line detection method, of a large amount of pure hydrocarbons with very high abundances.
The study is titled “Discovery of two cyanoderivatives of acenaphthylene (C12H8) in TMC-1 with the QUIJOTE line survey” and was published in the academic journal Astronomy & Astrophysics. (Source: CSIC)
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