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Detection of Acetamide (CH3CONH2): The Largest Interstellar Molecule With a Peptide Bond



J M. Hollis, Francis J. Lovas, A Remijan, P R. Jewell, Vadim V. Ilyushin, I Kleiner


Acetamide (CH3CONH2) has been detected in emission and absorption toward the star-forming region Sagittarius B2(N) with the 100-m Green Bank Telescope (GBT) by means of four A-species and four E-species rotational transitions. All transitions have energy levels less than 10 K. The SgrB2(N) cloud is known to have a cold halo with clumps of gas at several different velocities. Absorption features are largely characterized by local standard of rest (LSR) velocities that are typical of the two star-forming cores with systemic LSR velocities of +64 and +82 km s-1. Continuum sources embedded within the star-forming cores give rise to the absorption from the molecular gas halo surrounding the cores. Emission features are seen at an approximate intermediate LSR velocity of +73 km s-1 which characterizes the widespread molecular halo that has a spatial scale of a few arcminutes. Two low energy transitions of formamide (HCONH2) were also observed with the GBT toward Sagittarius B2(N) since formamide is the potential parent molecule of acetamide; both molecules are the only interstellar species with an NH2 group bound to a CO group, the so-called peptide bond, that provides the linkage for the polymerization of amino acids. While the acetamide transitions observed appear to be confined to the cold 8 K halo region, only the 110 - 000 transition of formamide appears to be exclusively from the cold halo; the 312- 313 transition of formamide is apparently contaminated with emission from the two hot cores. The relative abundance of acetamide to formamide is estimated to be in the range of 0.1 to 0.5 in the cold halo.
Astrophysical Letters & Communications


abundances, acetamide, interstellar cloud, interstellar molecule, microwave spectrum, radioastronomy, Sagittarius B2(N-LMH)


Hollis, J. , Lovas, F. , Remijan, A. , Jewell, P. , Ilyushin, V. and Kleiner, I. (2006), Detection of Acetamide (CH<sub>3</sub>CONH<sub>2</sub>): The Largest Interstellar Molecule With a Peptide Bond, Astrophysical Letters & Communications (Accessed April 24, 2024)
Created May 1, 2006, Updated October 12, 2021