Max Planck Institute for Radio Astronomy | 2014 Sep 25
Detection of iso-propyl cyanide with ALMA
Scientists from the Max Planck Institute for Radio Astronomy (Bonn, Germany), Cornell University (USA), and the University of Cologne (Germany) have for the first time detected a carbon-bearing molecule with a "branched" structure in interstellar space. The molecule, iso-propyl cyanide (i-C3H7CN), was discovered in a giant gas cloud called Sagittarius B2, a region of ongoing star formation close to the center of our galaxy that is a hot-spot for molecule-hunting astronomers. The branched structure of the carbon atoms within the iso-propyl cyanide molecule is unlike the straight-chain carbon backbone of other molecules that have been detected so far, including its sister molecule normal-propyl cyanide. The discovery of iso-propyl cyanide opens a new frontier in the complexity of molecules found in regions of star formation, and bodes well for the presence of amino acids, for which this branched structure is a key characteristic.
The results are published in this week’s issue of Science.
While various types of molecules have been detected in space, the kind of hydrogen-rich, carbon-bearing (organic) molecules that are most closely related to the ones necessary for life on Earth appear to be most plentiful in the gas clouds from which new stars are being formed. "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," says Arnaud Belloche from the Max Planck Institute for Radio Astronomy, the lead author of the paper.
The search for molecules in interstellar space began in the 1960's, and around 180 different molecular species have been discovered so far. Each type of molecule emits light at particular wavelengths, in its own characteristic pattern, or spectrum, acting like a fingerprint that allows it to be detected in space using radio telescopes.
Until now, the organic molecules discovered in star-forming regions have shared one major structural characteristic: they each consist of a "backbone" of carbon atoms that are arranged in a single and more or less straight chain. The new molecule discovered by the team, iso-propyl cyanide, is unique in that its underlying carbon structure branches off in a separate strand. "This is the first ever interstellar detection of a molecule with a branched carbon backbone," says Holger Müller, a spectroscopist at the University of Cologne and co-author on the paper, who measured the spectral fingerprint of the molecule in the laboratory, allowing it to be detected in space. ...
Detection of a branched alkyl molecule in the interstellar medium: iso-propyl cyanide - Arnaud Belloche et al
- Science 345(6204) 1584 (26 Sep 2014) DOI: 10.1126/science.1256678
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