In a paper published in this week’s issue of Science, astronomers from the Max Planck institute, the University of Cologne (Germany) and Cornell University (USA), announced to have for the first time detected, in interstellar space, a carbon-containing molecule with a branched structure. The molecule, isopropyl cyanide (i-C3H7CN), was discovered in a gas cloud called Sagittarius B2 close to the center of our galaxy. This region of ongoing star formation is heavily scrutinized by astronomers as it has been shown to be especially rich in hydrogen-containing, carbon-bearing (organic) molecules that are most closely related to the ones necessary for life on Earth. "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. Previous research had revealed the presence of a variety of molecules, (including ethylformate, the molecule responsible for the flavour of raspberries!) but until now they all consisted in a backbone of straight chain carbon atoms. The branched isopropyl cyanide (i-C3H7CN) is of special interest as this type of molecular arrangement is a key characteristic of amino acids, compounds associated with life
It is not only the structure of the molecule that surprised the team but also its abundance. It is almost half as plentiful as its sister molecule, normal-propylcyanide (n- C3H7CN). According to one of the coauthors, Robin Garrod, an astrochemist at Cornell University, "…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". The two molecules, each consisting of 12 atoms, are also the joint-largest molecules yet detected in any star-forming region.
The molecule was identified from its spectroscopic fingerprint using the newly established radio telescope station in the Atacama Desert in Chile. The area, the driest spot on earth, is especially suited for this type of observation. The Atacama Large Millimeter/submillimeter Array (ALMA), consisting of 66 radio antennas, most 12 meters in diameter, can create images that would require a 14,000 m single dish. Costing about US $1.4 billion it is the most expensive ground-based telescope on earth. It became fully operational in March 2013.
