Complex organic molecules discovered in the Large Magellanic Cloud

The Large Magellanic Cloud, the area N113 and the molecules detected (Image NRAO/AUI/NSF; ALMA (ESO/NAOJ/NRAO); Herschel/ESA; NASA/JPL-Caltech; NOAO)
The Large Magellanic Cloud, the area N113 and the molecules detected (Image NRAO/AUI/NSF; ALMA (ESO/NAOJ/NRAO); Herschel/ESA; NASA/JPL-Caltech; NOAO)

An article published in the journal “The Astrophysical Journal Letters” describes the detection of hot cores and the most complex molecules detected outside the Milky Way in the Large Magellanic Cloud, one of the Milky Way’s satellite dwarf galaxies. A team led by astronomer Marta Sewilo of NASA’s Goddard Space Flight Center used the ALMA radio telescope to conduct those measurements that contradict previous observations in what was considered a chemically primitive galaxy.

The Large Magellanic Cloud is relatively close to the Milky Way and has consequently been the subject of many studies, also to analyze its chemical composition. Until now it looked similar to distant galaxies we see as they were when the universe was young. In these galaxies heavy elements are still rare because it takes a number of generations of stars to form them. In technical jargon, that scarcity of heavy elements is called low metallicity.

Dwarf galaxies such as the Large Magellanic Cloud have a slow stellar formation rate compared to larger galaxies and that’s why astronomers were not surprised to detect low metallicity there as well. Instead, new observations that took advantage of the power and sensitivity of the ALMA (Atacama Large Millimeter/submillimeter Array) radio telescope, inaugurated in March 2013, revealed a different situation.

Methanol is a fairly common substance in space being the simplest form of alcohol and previous observations detected traces of this substance even in the Large Magellanic Cloud. However, this time the ALMA radio telescope also detected the chemical signature of dimethyl ether and methyl formate. These are two molecules more complex than methanol, the most complex discovered so far outside the Milky Way and just where their discovery wasn not expected.

This research focused in particular on a star-formation region within the Large Magellanic Cloud referred to as N113. It’s a sort of nursery for new stars already studied in the past with NASA’s Spitzer space telescope and ESA’s Herschel Space Observatory, which detected the infrared glow of many protostars.

The presence of organic molecules, even complex, in that kind of environment, is very interesting. Discussions about the origin of life’s building blocks are often heated but more and more molecules of that type are discovered in space. Finding them in a galaxy with primitive characteristics suggests that at least some basis for the birth of life forms already existed when the universe was young.

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