Largest alcohol molecule found in space may hold key to star formation

There is alcohol in the room. No, they are not bottles of wine thrown away by careless astronauts; rather it is in microscopic molecular form. Now researchers think they’ve discovered the largest alcohol molecule to date in space, 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 was first detected in a star-forming region, and isopropanol (the main ingredient in hand sanitizer), which has never been seen before in interstellar space. shape is seen.

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 formation mechanism of each,” says astrochemist Rob Garrod from the University of Virginia. “Because they look so much alike, they behave physically in very similar ways, meaning the two molecules must be present in the same places at the same time.”

“The only open question is the exact amounts that are present – this makes their interstellar ratio much more precise than would be the case for other pairs of molecules. It also means that the chemical network can be tuned much more precisely to determine the mechanisms by which they act.” to shape.”

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

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

ALMA offers higher resolution and sensitivity, allowing researchers to identify molecules that were previously invisible. Being able to discern the specific radiation frequency emitted by any molecule in a crowded area of ​​space such as Sgr B2 is crucial in 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 contributing to the observed radiation that their spectra overlap and it is difficult to disentangle their fingerprints and identify them individually.”

The discovery was made thanks to ALMA’s ability to detect very narrow spectral lines, and to lab work that extensively mapped the signatures propanolisomers would give off in space.

By finding molecules that are closely linked — such as normal-propanol and iso-propanol — and measuring how abundant they are relative to each other, scientists can take a closer look at the chemical reactions that triggered them.

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

“There are still many unidentified spectral lines in the ALMA spectrum of Sgr B2, meaning 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, expanding ALMA instrumentation to lower frequencies will likely help us reduce spectral confusion even further and potentially allow for the identification of additional organic molecules in this spectacular resource.”

The research was published in Astronomy and Astrophysics here and here

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