title: Observations of interstellar formamide: availability of a prebiotic precursor in the galactic habitable zone.
abstract: We conducted a study on interstellar formamide, NH2CHO, toward star-forming regions of dense molecular clouds, using the telescopes of the Arizona Radio Observatory (ARO). The Kitt Peak 12 m antenna and the Submillimeter Telescope (SMT) were used to measure multiple rotational transitions of this molecule between 100 and 250 GHz. Four new sources of formamide were found [W51M, M17 SW, G34.3, and DR21(OH)], and complementary data were obtained toward Orion-KL, W3(OH), and NGC 7538. From these observations, column densities for formamide were determined to be in the range of 1.1×10(12) to 9.1×10(13) cm(-2), with rotational temperatures of 70-177 K. The molecule is thus present in warm gas, with abundances relative to H2 of 1×10(-11) to 1×10(-10). It appears to be a common constituent of star-forming regions that foster planetary systems within the galactic habitable zone, with abundances comparable to that found in comet Hale-Bopp. Formamide's presence in comets and molecular clouds suggests that the compound could have been brought to Earth by exogenous delivery, perhaps with an infall flux as high as ~0.1 mol/km(2)/yr or 0.18 mmol/m(2) in a single impact. Formamide has recently been proposed as a single-carbon, prebiotic source of nucleobases and nucleic acids. This study suggests that a sufficient amount of NH2CHO could have been available for such chemistry.
authors: Department of Chemistry and Steward Observatory, University of Arizona, Tucson, Arizona 85721-0065, USA.
authors: Gilles R
authors: GR
authors: Adande
authors: Neville J
authors: NJ
authors: Woolf
authors: Lucy M
authors: LM
authors: Ziurys
mesh_terms: D017753:Ecosystem; D005118:Extraterrestrial Environment; D005559:Formamides / Q000737:chemistry*; D006868:Hydrolysis; D011789:Quantum Theory
chemical_list: D005559:Formamides; C031066:formamide
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