Researchers detected a carbon-bearing molecule with a "branched" structure in space for the first time; the finding is significant because these types of molecules may indicate the presence of amino acids, a "building block" of life.
A number of types of molecules have been detected in space in the past, but the type that is hydrogen-rich and carbon-based (meaning most closely related to those on Earth) appear to be most abundant in star-forming gas clouds, the Max Planck Institute for Radio Astronomy reported.
"Understanding the production of organic material at the early stages of star formation is critical to piecing together the gradual progression from simple molecules to potentially life-bearing chemistry," said Arnaud Belloche from the Max Planck Institute for Radio Astronomy, the lead author of the paper.
Different types of molecules emit light at particular wavelengths, acting as a sort of "fingerprint." Until now all the molecules had one feature in common, a "backbone" of carbon atoms arranged in a chain. The iso-propyl cyanide molecule is unique because its underlying carbon structure branches off into different strands.
"The enormous abundance of iso-propyl cyanide suggests that branched molecules may in fact be the rule, rather than the exception, in the interstellar medium," said Robin Garrod, an astrochemist at Cornell University and a co-author of the paper.
To make their findings the researchers used the Atacama Large Millimeter/submillimeter Array (ALMA), in Chile to look at the molecular content of the star-forming region Sagittarius B2 (Sgr B2).
"Thanks to the new capabilities offered by ALMA, we were able to perform a full spectral survey toward Sgr B2 at wavelengths between 2.7 and 3.6 mm, with sensitivity and spatial resolution 10 times greater than our previous survey," Belloche said.
The findings also only took about one-tenth of the time as the previous survey. By looking at predictions made through the Cologne Database for Molecular Spectroscopy, the team identified emission features from two varieties of propyl cyanide.
The researchers constructed a computational model that simulated the chemistry of formation of the molecules detected in Sgr B2. Both types of propyl cyanide were found to be formed on the surface of interstellar dust grains.
"The detection of iso-propyl cyanide tells us that amino acids could indeed be present in the interstellar medium because the side-chain structure is a key characteristic of these molecules," said Karl Menten, director at MPIfR and head of its Millimeter and Submillimeter Astronomy research department. "Amino acids have already been identified in meteorites and we hope to detect them in the interstellar medium in the future."
The research was published in this week's edition of the journal Science.
