Astrochemists Find New Organic Molecule in Milky Way’s Interstellar Space

Scientists have detected an organic molecule close to the core of our galaxy in a giant cloud in the interstellar medium for the first time in history. The molecule is known as propargylamine and could be of significant importance in the shaping of the amino acids crucial for the appearance of life 

“The peculiarity of this chemical species lies in its carbon-nitrogen double bond, which gives it a high reactivity,” explained astrochemist Luca Bizzocchi of the Max Planck Institute for Extraterrestrial Physics in Germany.  

“With this double bond, it becomes a fundamental constituent of the chemical chains that lead from the simplest and most abundant molecules in space containing carbon and nitrogen – for example formaldehyde (H2CO) and ammonia (NH3), respectively – to the more complex amino acids, the fundamental building blocks of terrestrial biology.”  

What is Propargylamine?

The area in which the molecule was discovered is a system of clouds filled with molecular gas in the Milky Way. It is called the ‘Central Molecular Zone,’ a region of importance for astrochemists. It is a large repository of astrophysical complex organic molecules, which include ethyl formate, isopropyl cyanide, and propylene oxide. These are known as prebiotic molecules, because they play a role in prebiotic processes that develop the building blocks of life, such as amino acids, RNA, and DNA 

Propargylamine can also be rather significant for these processes, as they are molecules with a double carbonnitrogen bond which have an important role in a chemical process known as the Strecker synthesis, used to develop amino acids in lab environments.  

Moreover, propargylamine is structurally similar to a few organic molecules that have already been detected in space. Therefore, Bizzocchi and his team decided to give it a shot, but first, they had to know what they were searching for, which meant analyzing the spectrum of propargylamine in a lab setting.

The Central Molecular Zone. [Image: NASA/CXC/UMass/D. Wang et al.; NRF/SARAO/MeerKAT]
When light passes through a molecular cloud, the molecules in that cloud assimilate and re-transmit electromagnetic radiation at certain wavelengths, which results in what it is known as absorption and emission lines on an electromagnetic range. Each molecule has its own structure of these lines, similar to a chemical fingerprint, but scientists need to know what the print looks like in order to detect it.  

“As a molecule rotates in the interstellar medium, it emits photons at very precise frequencies,” Bizzocchi explained. “This information, when combined with data from radio telescopes, allows us to know whether a molecule is present in the molecular clouds, the sites of star and planet formation.”  

How Researchers Found the Molecule  

Therefore, the team registered the rotational spectra of two isomers, or atomic configurations, of propargylamine in the lab, summing up to approximately 1,000 rotational transitions. This enabled the team to create a highly accurate spectral profile of propargylamine, explaining the distortion the molecule encounters in space.  

The next step was to compare the outcome with the spectral data. The information was collected using the 30-meter telescope located in Sierra Nevada, Spain, which was focused on a cloud in the Central Molecular Zone known as G+0.693-0.027.  

“Our molecule was already there,” said astrophysicist Víctor M. Rivilla of the National Institute for Astrophysics in Italy. “It was laying in our data of the G+0.693-0.027 molecular cloud, but we couldn’t identify it without knowing its precise spectroscopy, that is the full description of its emission frequency pattern. As soon as we got it, thanks to the measurements in the laboratory, we realized that the propargylamine was undoubtedly there, waiting for someone to recognize it.”  

A paper detailing the findings was published in the journal Astronomy & Astrophysics, and it is also available on arXiv.   

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