BY KEITH COOPER
Posted: 21 April, 2009
An interstellar cloud of gas close to the galactic centre rich in a veritable soup of chemicals has produced its two most complex molecules yet, which are just a step away from organic molecules that are the basis of life as we know it.
The results, presented today at the National Astronomy Meeting at the University of Hertfordshire, reveal the discovery of ethyl formate and n-propyl cyanide in the star-forming nebula Sagittarius B2. This star-generating cloud contains enough gas and dust to produce three million Suns, and lies just less than 400 light years from the galactic centre itself.
Finding these molecules, which are the most complex ever found in interstellar space, was not easy for the German and American researchers at the Max Planck Institute for Radio Astronomy, the University of Cologne and Cornell University. The larger a molecule is, the more difficult it is to detect because the emitted radiation is spread out across various emission lines, weakening the signal that was detected by the 30-metre IRAM radio astronomy telescope in Spain.
Nevertheless, their discovery raises hope that molecules such as simple amino acids like glycine could also exist in star-forming nebulae. By running computer simulations, the researchers saw that complex molecules build up like Lego blocks, adding together pre-formed molecules such as methanol, rather than being assembled from scratch around nucleating sites such as dust grains.
"There is no apparent limit to the size of molecules that can be formed by this process, so there's good reason to suspect that even more complex organic molecules to be there, if we can detect them," says Cornell's Robin Garrod.
The implications of the discovery of a fully-fledged amino acid in the interstellar firmament would be profound, telling us that the basic materials of life here on Earth first began out there.