(ORDO NEWS) — There is alcohol in space. No, these are not bottles of wine thrown away by careless astronauts; rather, it is in microscopic molecular form. Now, researchers think they’ve found the largest alcohol molecule in space, in the form of propanol.
Propanol molecules exist in two forms, or isomers, both of which have now been identified in observations: the normal propanol, which was first discovered in a star-forming region, and isopropanol (a key ingredient in hand sanitizer), which has never before been observed in interstellar form.
These discoveries should shed light on how celestial bodies such as comets and stars are formed.
“Detecting both isomers of propanol is a unique tool for determining the mechanism of formation of each,” says astrochemist Rob Garrod of the University of Virginia. “Because they are so similar to each other, physically they behave very similarly, which means that two molecules must be in the same places at the same time.”
“The only open question is the exact quantities present this makes their interstellar ratio much more accurate than is the case with other pairs of molecules. It also means that the chemical network can be tuned much more carefully to determine the mechanisms by which they form.”
These alcohol molecules have been found in the so-called “birthplace” of stars, a giant star-forming region called Sagittarius B2 (Sgr B2). This region is near the center of the Milky Way and not far from Sagittarius A* (Sgr A*), the supermassive black hole around which our galaxy is built.
While such deep-space molecular analysis has been going on for more than 15 years, the arrival of the Atacama Large Millimeter/submmillimeter Array (ALMA) telescope in Chile 10 years ago has raised the level of detail that astronomers can access.
ALMA offers a higher level of detail. resolution and a higher level of sensitivity, allowing researchers to identify molecules that were not previously visible. Being able to isolate the specific emission frequency of each molecule in a busy part of space, such as Sgr B2, is critical to calculating what is 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 contributing to the observed emission that their spectra overlap, and it’s hard to disentangle their fingerprints and identify them individually.”
Thanks to how ALMA can detect very narrow spectral lines, as well as lab work that has comprehensively characterized the signatures that propanol isomers will emit in space, the discovery has been made.
Finding closely related molecules like normal propanol and isopropanol and measuring how common they are in relation to each other allows scientists to study in greater detail the chemical reactions that produced them.
Work continues to find more interstellar molecules in Sgr B2, and to understand the sort of chemical melting pot that leads to star formation. The organic molecules isopropyl cyanide, N-methylformamide, and urea have also been detected by ALMA.
“There are still many unidentified spectral lines in the spectrum of ALMA Sgr B2, which means that there is still a lot to decipher its chemical composition,” says astronomer Carl Menten from the Institute of Radio Astronomy. Max Planck in Germany.
“In the near future, extending ALMA’s capabilities to lower frequencies will likely help us further reduce spectral confusion and possibly allow us to identify additional organic molecules in this impressive source.”
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