Building blocks of life can form long before stars, a new study shows.
An international team of astrophysicists and astrochemical modelers, mostly based at the Laboratory for Astrophysics at Leiden Observatory, the Netherlands, has shown that glycine, an important building block of life, can form under the harsh conditions of space. The study is published in Nature Astronomy suggests that glycine and other amino acids can form in the dense interstellar clouds of space well before new stars and planets are formed.
Methylamine, the precursor of glycine, was detected in the coma of comet 67P/Churyumov-Gerasimenko and in the samples returned by the stardust mission, suggesting amino acids form long before stars. Comets are the most pristine materials in our solar system and represent the Sun and other planets’ molecular composition just before their formation. This contradicts the earlier theory that suggests that UV radiation is required to produce glycine.
The study has shown the possibility of glycine formation on the surface of icy dust grains in the absence of energy through dark chemistry. Dark chemistry refers to chemistry without the need for energetic radiation.
According to the lead author, Dr. Sergio Ioppolo, from the Queen Mary University of London, they simulated the conditions of dark stellar clouds in a laboratory setting wherein a thin layer of ice covers cold dust particles. Subsequent impacts of atoms caused precursor species to fragment and reactive intermediates to recombine.
The scientists showed methylamine could form. They were also able to confirm glycine formation using a unique ultra-high vacuum setup, equipped with a series of atomic beamlines and accurate diagnostic tools. The presence of water ice was essential in this process.
The experimental results were confirmed using astrochemical models and allowed the researchers to extrapolate the data obtained on just a day to interstellar conditions, bridging millions of years.
According to Harold Linnartz, Director of the Laboratory for Astrophysics at Leiden Observatory, “Such an early formation of glycine in the evolution of star-forming regions implies that this amino acid can be formed more ubiquitously in space and is preserved in the bulk of ice before inclusion in comets and planetesimals that make up the material from which ultimately planets are made.”
According to Dr. Ioppolo, glycine can become a precursor to other complex organic molecules. In principle, the same mechanism can add other functional groups to the glycine backbone, forming other amino acids such as alanine and serine in dark clouds of space. Eventually, this organic matter gets delivered to young planets like our Earth through comets and other celestial bodies.
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