The largest alcohol molecule in space is in the form of propanol.
REPUBLIKA.CO.ID, VIRGINIA— There is alcohol in space in the form of microscopic molecules. Now researchers think they have found largest alcohol molecule in space, in the form of propanol.
Molecule propanol exists in two forms, or isomers, both of which have now been identified in observations: normal propanol, which has been detected in the star-forming region for the first time, and isopropanol (a key ingredient in hand sanitizer), which has never been seen in interstellar form before.
Reporting from Sciencealert, Sunday (3/7/2022), this discovery should explain how celestial bodies such as comets and stars are formed.
“The detection of the two propanol isomers is very powerful in determining the mechanism of formation of each,” says astrochemist Rob Garrod of the University of Virginia, “Because they are so similar to each other, they behave physically in very similar ways, which means that the two molecules must be in the same place at the same time.”
“The only open question is the exact number present—this makes their interstellar ratio much more precise than it would be for other pairs of molecules. It also means that chemical networks can be fine-tuned to determine the mechanism by which they form,” Garrod said.
This alcohol molecule has been found in what is known as the stellar ‘delivery space’, the region of a giant star-forming giant called Sagittarius B2 (Sgr B2). This region is located near the center of the Milky Way and close to Sagittarius A* (Sgr A*), the supermassive black hole on which our galaxy is built.
While this kind of deep-space molecular analysis has been going on for more than 15 years, the arrival of the Atacama Large Millimeter/submillimeter Array (ALMA) telescope in Chile 10 years ago has increased the level of detail accessible to astronomers.
ALMA offers higher resolution and a greater degree of sensitivity, allowing researchers to identify molecules not seen before. Being able to choose the specific frequency of radiation emitted by each molecule in a busy part of space like Sgr B2 is crucial in calculating what’s out there.
“The bigger the molecule, the more spectral lines at different frequencies it produces,” says physicist Holger Müller of the University of Cologne in Germany. “In a source like Sgr B2, there are so many molecules that contribute to the observed radiation that the spectra overlap and it is difficult to decipher the fingerprints and identify them individually.”
Thanks to the way ALMA was able to detect very narrow spectral lines, as well as laboratory work comprehensively characterizing the signatures that propanol isomers would provide in space, the discovery was made.
Finding closely related molecules – such as normal propanol and isopropanol – and measuring how much they are relative to one another, allows scientists to take a closer look at the chemical reactions that produce them.
Work continues to find more interstellar molecules in Sgr B2, and to understand the types of chemical fusion that lead to star formation. The organic molecules of isopropyl cyanide, N-methylformamide, and urea have also been discovered by ALMA.
“There are still many unknown spectral lines in the spectrum of ALMA Sgr B2 which means there is still a lot of work left to decipher its chemical composition,” said astronomer Karl Menten of the Max Planck Institute for Radio Astronomy in Germany.
“In the near term, the expansion of ALMA instrumentation to lower frequencies is likely to help us reduce spectral confusion even further and possibly allow the identification of additional organic molecules in this spectacular source,” he said.
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