Identification of Nitriles in the Interstellar Medium Yvonne J. Pendleton The interstellar 4.62-micron band (2165 wavenumber) may be an important contributor to the cyanide (CN) inventory of material available for incorporation into newly forming planetary systems. This band is seen in absorption along lines of sight that pass through icy grains in front of embedded protostars. Therefore, the identification of the interstellar band is important for two reasons: for the astrophysical understanding of organic material in the dense cloud environment, and for the potential relevance to the origin of life, because extraterrestrial early Earth had a nonreducing environment. New laboratory results indicate that carbon, nitrogen, oxygen, and hydrogen are active participants in the carrier of the interstellar 4.62-micron band. Results show that ion bombardment of interstellar ice analogs readily produces a band in laboratory residues that is remarkably similar in profile and peak position to that seen in the dense interstellar medium. A shift in band position resulting from deuterium substitution demonstrates that hydrogen is a component of the carrier in the laboratory-produced 4.62-micron band. This finding is in contrast to premature identifications of the isocyanate anion, OCN-, published recently by other groups. Irradiation of ices through ion bombardment allows testing mixtures that include solid nitrogen, N2, a possible source of the available nitrogen in dense cloud ices. If the atmosphere of the early Earth were not overly reducing, as some studies indicate, extraterrestrial sources of CN-bearing molecules may have been necessary for the origin of life, the in situ production of prebiotic molecules containing the cyanogen bond would have been difficult. Therefore, the identification of the interstellar 4.62-micron band may include the identification of an extraterrestrial source of CN. Point of Contact: Y. Pendleton (650) 604-4391 ypendleton@mail.arc.nasa.gov Back To Top Previous Paper Return to Astrophysics Next Paper

Research & Technology 1999
NASA Ames Research Center