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Glycine, the simplest amino acid and a major component of life, can form in dense interstellar clouds before they turn into new stars and planets, as published Monday in “Nature Astronomy”.
An international team of scientists has shown that glycine, and most likely other amino acids, can form under the harsh conditions that govern chemistry in space.
Comets are the most pristine material in our Solar System and reflect the molecular composition present at the time our Sun and our planets were about to form.
Detection of glycine in the coma (gas surrounding the nucleus) of comet 67P / Churyumov-Gerasimenko suggests that amino acids, such as glycine, are formed long before stars, say experts, including Queen Mary University of London.
That comet was discovered in 1969 by the Soviet scientist Klim Ivanovich Churimov. In 2014, the Rosetta spacecraft got close enough to take pictures in great detail.
Until recently it was thought that the formation of glycine required energy, creating limitations on the environment in which it could form.
In the new study, the team of astrophysicists showed that it is possible for glycine to form on the surface of frozen dust grains, in the absence of energy, through dark chemistry.
The results contradict previous studies that suggested ultraviolet radiation was needed to produce this molecule.
This was stated by the expert Sergio Ioppolo, of Queen Mary University of London and lead author of the article “Dark chemistry refers to chemistry without the need for energy radiation” and added that “in the laboratory we have been able to simulate the conditions in dark interstellar clouds.”
Scientists have shown that methylamine, the precursor species of glycine that was detected in the coma of comet 67P, could form and subsequently, with a more precise diagnosis, they were able to confirm that glycine could also form and that the presence of ice water was essential in this process.
Further research using astrochemical models confirmed the experimental results and allowed the researchers to extrapolate the data obtained on a typical laboratory time scale of just one day to interstellar conditions, combining millions of years.
“From this, we found that low but substantial amounts of glycine can form in space over time.”said Herma Cuppen of Radboud University Nijmegen, the Netherlands, who is responsible for some modeling studies.
“The important conclusion of this work is that the molecules considered basic components of life have already formed at a stage long before the formation of stars and planets began.”said Harold Linnartz, director of the astrophysics laboratory at the Leiden Observatory.
“Such early formation of glycine in the evolution of star-forming regions implies that this amino acid can form more ubiquitously in space and is conserved in most of the ice before inclusion in the comets and planetesimals (solid objects) that make up the material of which the planets are made of “, Ioppolo indicated.
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