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arXiv · 1712.09548

First detection of cyanamide (NH$_2$CN) towards solar-type protostars

A. Coutens·E. R. Willis·R. T. Garrod·H. S. P. Müller·T. L. Bourke·H. Calcutt·M. N. Drozdovskaya·J. K. Jørgensen·N. F. W. Ligterink·M. V. Persson·G. Stéphan·M. H. D. van der Wiel·E. F. van Dishoeck·S. F. Wampfler
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Abstract

Searches for the prebiotically-relevant cyanamide (NH$_2$CN) towards solar-type protostars have not been reported in the literature. We here present the first detection of this species in the warm gas 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 from the IRAM Plateau de Bure Interferometer of NGC1333 IRAS2A. We furthermore detect the deuterated and $^{13}$C isotopologues of NH$_2$CN towards IRAS 16293-2422 B. This is the first detection of NHDCN in the interstellar medium. Based on a local thermodynamic equilibrium analysis, we find that the deuteration of cyanamide ($\sim$ 1.7%) is similar to that of formamide (NH$_2$CHO), which may suggest that these two molecules share NH$_2$ as a common precursor. The NH$_2$CN/NH$_2$CHO abundance ratio is about 0.2 for IRAS 16293-2422 B and 0.02 for IRAS2A, which is comparable to the range of values found for Sgr B2. We explored the possible formation of NH$_2$CN on grains through the NH$_2$ + CN reaction using the chemical model MAGICKAL. Grain-surface chemistry appears capable of reproducing the gas-phase abundance of NH$_2$CN with the correct choice of physical parameters.

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A. Coutens, E. R. Willis, R. T. Garrod, H. S. P. Müller, T. L. Bourke, H. Calcutt, M. N. Drozdovskaya, J. K. Jørgensen, N. F. W. Ligterink, M. V. Persson, G. Stéphan, M. H. D. van der Wiel, E. F. van Dishoeck, S. F. Wampfler. 2017-12-27. First detection of cyanamide (NH$_2$CN) towards solar-type protostars. https://doi.org/10.1051/0004-6361%2F201732346

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