William Atkins
Wednesday, 22 April 2009 20:21
Science -
Space
Page 2 of 3
The paper announcing their discovery is entitled “
Increased complexity in interstellar chemistry: Detection and chemical modeling of ethyl formate and n-propyl cyanide in Sgr B2(N).” It was submitted in
arXiv.org on February 26, 2009.
They state in the abstract to their paper,
“In recent years, organic molecules of increasing complexity have been found toward the prolific Galactic center source Sagittarius B2. We wish to explore the degree of complexity that the interstellar chemistry can reach in star-forming regions. We carried out a complete line survey of the hot cores Sgr B2(N) and (M) with the IRAM 30 m telescope in the 3 mm range.”
“We analyzed this spectral survey in the LTE [local thermodynamic equilibrium] approximation. We modeled the emission of all known molecules simultaneously, which allows us to search for less abundant, more complex molecules. We compared the derived column densities with the predictions of a coupled gas-phase and grain-surface chemical code.”
“We report the first detection in space of ethyl formate (C2H5OCHO) and n-propyl cyanide (C3H7CN) toward Sgr B2(N). The abundances of ethyl formate and n-propyl cyanide relative to H2 are estimated to be 3.6e-9 and 1.0e-9, respectively. Our chemical modeling suggests that the sequential, piecewise construction of ethyl and n-propyl cyanide from their constituent functional groups on the grain surfaces is their most likely formation route. Ethyl formate is primarily formed on the grains by adding CH3 to functional-group radicals derived from methyl formate, although ethanol may also be a precursor.“
It is difficult for these scientits to locate such complex molecules out in interstellar space because their spectral features are difficult to identify.
In fact, one of the authors, Arnaud Belloche, states, "
The difficulty in searching for complex molecules is that the best astronomical sources contain so many different molecules that their "fingerprints" overlap, and are difficult to disentangle.” [ScienceDaily.com]
Holger Mueller, another author, added, "Larger molecules are even more difficult to identify because their "fingerprints" are barely visible: their radiation is distributed over many more lines that are much weaker.” [ScienceDaily.com]
Page three concludes.
