Urea is first detected outside a stellar formation region


Figure: An image obtained by NASA's Spitzer Space Telescope showing the center of our Galaxy. The yellow star indicates the position of the galactic center and the green star the position of the molecular cloud studied in this work, G+0.693-0.027, where urea has been found. Credit: Victor M. Rivilla (INAF- Osservatorio Astrophysical de Arcetri and co-author of the study) and NASA Spitzer Space Telescope, IRAC camera.

An international team, led by researchers from the Centro de Astrobiología (CAB, CSIC-INTA), has detected urea in the Galactic Center's G+0.693-027 molecular cloud for the first time. This is the second time urea has been detected in space, which would indicate that we are facing a common element in the chemistry of the interstellar environment. Studies like this try to find out if key prebiotic molecules in the chemical scheme of RNA world theories, such as urea, could form and be present in the interstellar environment.

One of the goals of astrobiology is to understand the origin of life, for which different theories have developed throughout history. One of them is world-based RNA (ribonucleic acid), which argues that life arose from the activity of RNA molecules and their ability to store, transmit and duplicate genetic information. This hypothesis gives the RNA a central role in the process of the origin of life. 

Thus, a scientific team, led by researchers from the Centro de Astrobiología, has conducted a study in which they have sought in the interstellar environment some of these key prebiotic molecules in the chemical scheme of theories of the world RNA. It is the case of urea and 2-amino-oxazole, key pieces in the formation of nucleotide ribo (the basic compounds of RNA) and in simple sugars such as glyceraldehyde or dihydroxyketone. A year earlier, the same team found two other key molecules in the interstellar medium for the first time: the glicolonitrile and the Z-denominational cianometanimine.com. "Except for 2-amino-oxazole, previous studies had sought these molecules in other regions of the sky; however, they had done so in isolation, regardless of the astrobiological point of view," explains Izaskun Jiménez-Serra, CAB researcher and study leader.

This time, researchers have sought these molecules together to characterize whether interstellar chemistry can achieve a complexity similar to that that which could give rise to life according to theories of the RNA world. For this they have used deep spectral sweeps obtained towards two astronomical sources very rich in complex organic molecules: the solar-type protostar IRAS16293-2422 B and the molecular cloud G+0.693-0.027 in the center of the Milky Way.

This new article, recently published in the journal Astrobiology, captures the second detection of urea in space and the first outside of a stellar formation region in the G+0.693-0.027 molecular cloud of the Galactic Center (the first urea detection was performed last year in the SgrB2 N mass star formation region). "This new detection indicates that urea would be a typical and common product of interstellar media chemistry," says Izaskun Jiménez-Serra.

The results of this study thus suggest that key molecules in the chemical scheme of the RNA world could already form in space. Once formed, they could later be incorporated into minor objects such as comets and asteroids in planetary systems, which would eventually fall on the surface of young planets similar to what Earth was 3.8 billion years ago. These objects, and their prebiotic material, could boost initial chemical reactions towards the formation of ribonucletotics within the RNA world scheme. 

"In the future we want to continue to look for more of these molecules by performing deep spectral sweeps in all atmospheric windows at millimeter and centimeter wavelengths," explains Jiménez-Serra.


Fuente: UCC-CAB

Fecha: 2020-04-27


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