First detection of cyanamide (NH2CN) towards solar-type protostars

Abstract : Cyanamide (NH _{2}CN) is thought to be an important pre-biotic molecule, as it is converted to urea in liquid water (Kilpatrick 1947). Despite being detected in external galaxies (Martín et al. 2006; Aladro et al. 2011), NH _{2}CN has only previously been detected twice in the Milky Way, in Sgr B2 (Turner et al. 1975) and Orion KL (White et al. 2003). Here we report the first detection of NH _{2}CN surrounding two solar-type protostars, using data from the Atacama Large Millimeter/submillimeter Array Protostellar Interferometric Line Survey (PILS) of IRAS 16293-2422 B and observations of NGC1333 IRAS2A taken with the IRAM Plateau de Bure Interferometer. Towards IRAS 16293B, we also detect the deuterated and ^{13}C isotopologues of NH _{2}CN, constituting the first interstellar detection of NHDCN. LTE analysis shows that the deuteration of cyanamide (˜ 1.7%) is similar to that of formamide (NH _{2}CHO), perhaps suggesting a common molecular precursor to both. The NH _{2}CN/NH _{2}CHO abundance ratio varies between the sources, being 0.2 for IRAS 16293-2422B and ˜ 0.02 for IRAS2A. These values are comparable to observed values for Sgr B2. We use the three-phase chemical kinetics model MAGICKAL to investigate the formation and destruction of this molecule. Production of NH _{2}CN on the surface of grains through the combination of NH _{2} and CN radicals was added to our network, and it is demonstrated that our model can reproduce observed gas-phase abundances of NH _{2}CN, depending on the choice of the gas-phase density. The NH _{2}CN/NH _{2}CHO abundance ratio is still too low however, which is perhaps related to overproduction of NH _{2}CHO. [1] Kilpatrick, M. L. 1947, J. Am. Chem. Soc., 69, 40[2] Martín, S., Mauersberger, R., Martín-Pintado, J., Henkel, C., & García-Burillo, S. 2006, ApJS, 164, 450[3] Aladro, R., Martín, S., Martín-Pintado, J., et al. 2011, A&A, 535, A84[4] Turner, B. E., Liszt, H. S., Kaifu, N., & Kisliakov, A. G. 1975, ApJ, 201, L149[5] White, G. J., Araki, M., Greaves, J. S., Ohishi, M., & Higginbottom, N. S. 2003, A&A, 407, 589
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Communication dans un congrès
42nd COSPAR Scientific Assembly. Held 14-22 July 2018, in Pasadena, California, USA, Abstract id. F3.2-4-18., Jul 2018, Pasadena, United States. 2018
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https://hal.archives-ouvertes.fr/hal-01901782
Contributeur : Marie-Paule Pomies <>
Soumis le : mardi 23 octobre 2018 - 11:22:35
Dernière modification le : vendredi 16 novembre 2018 - 02:20:23

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Eric Willis, Ewine Van Dishoeck, Robin Garrod, Maria Drozdovskaya, Jes Kristian Jørgensen, et al.. First detection of cyanamide (NH2CN) towards solar-type protostars. 42nd COSPAR Scientific Assembly. Held 14-22 July 2018, in Pasadena, California, USA, Abstract id. F3.2-4-18., Jul 2018, Pasadena, United States. 2018. 〈hal-01901782〉

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