The largest alcohol molecule found in space but may be the key to star formation

The largest alcohol molecule found in space but may be the key to star formation

There is alcohol in space. No, it’s not bottles of wine that are thrown away by careless astronauts; rather, it is in microscopic molecular form. Now scientists believe they have discovered the largest alcohol molecule in space to date, in the form of propanol.

Propanol molecules exist in two forms, or isomers, both of which have now been identified in observations: normal propanol, which has been discovered in a star-forming region for the first time, and isopropanol (the key ingredient in hand sanitizers), which has never been seen in interstellar form before.

These discoveries should shed light on how celestial bodies such as comets and stars are formed.

“The detection of both isomers of propanol is uniquely powerful in determining the mechanism of formation of each,” says astrochemist Rob Garrod from 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 present in the same places at the same times.”

“The only open question is the exact amounts that exist – this makes their interstellar relationship much more accurate than would be the case for other molecular pairs. It also means that the chemical network can be tuned much more accurately to determine the mechanisms by which they forms. “

These alcohol molecules have been found in what is called a “birth room” of stars, the giant star-forming region called Sagittarius B2 (Sgr B2). The region is close to the center of the Milky Way and close to Sagittarius A * (Sgr A *), the supermassive black hole which our galaxy is built around.

Although this type of molecular analysis of space has been going on for more than 15 years, the arrival of Atacama Large Millimeter / submillimeter Array The (ALMA) telescope in Chile 10 years ago has increased the level of detail that astronomers can access.

ALMA offers a higher resolution and a higher level of sensitivity, enabling researchers to identify molecules that were not previously visible. Being able to take apart the specific radiation frequency emitted by each molecule in a occupied part of space as Sgr B2 is crucial for calculating what is out there.

“The larger the molecule, the more spectral lines at different frequencies it produces,” says physicist Holger Müller from the University of Cologne in Germany. “In a source like Sgr B2, there are so many molecules that contribute to the observed radiation that their spectra overlap and it is difficult to solve their fingerprints and identify them individually.”

Thanks to the way in which ALMA can detect very narrow spectral lines, as well as lab work that comprehensively characterized the signatures that propanol isomers would emit in space, the discovery was made.

Finding molecules that are closely linked – such as normal propanol and isopropanol – and measuring how many they are in relation to each other, allows researchers to look in more detail at the chemical reactions that have caused them.

The work continues to discover more interstellar molecules in Sgr B2, and to understand the type of chemical crucible that leads to star formation. The organic molecules isopropyl cyanide, N-methylformamide and urea have also been discovered by ALMA.

“There are still many unidentified spectral lines in the ALMA spectrum of Sgr B2, which means that much work remains to be done to decipher its chemical composition.” says astronomer Karl Menten from the Max Planck Institute for Radio Astronomy in Germany.

“In the near future, the expansion of ALMA instrumentation down to lower frequencies is likely to help us further reduce spectral confusion and possibly enable the identification of additional organic molecules in this spectacular source.”

The research has been published in Astronomy & Astrophysics here and here.

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