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

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.

Accepted in A&A