Detection of Interstellar Cyanoformaldehyde (CNCHO)

Cyanoformaldehyde (CNCHO) has been detected toward the star-forming region Sagittarius B2(N) with the 100 m Green Bank Telescope (GBT) by means of four P-branch rotational transitions in emission, the 7(0, 7)-6(1, 6) at 8.6 GHz, the 8(0, 8)-7(1, 7) at 19.4 GHz, the 9(0, 9)-8(1, 8) at 30.3 GHz, and the 10(0, 10)-9(1, 9) at 41.3 GHz, and one P-branch transition in absorption, the 5(1, 5)-6(0, 6) at 2.1 GHz. The five b-type transitions have favorable transition line strengths (S_ijμ² > 10 D²) and occur in spectral regions that have little possibility of confusion with other molecular species. The transition line strengths and energy levels involved in the four cyanoformaldehyde transitions in emission are similar; however, transitions with larger beam sizes give systematically higher column densities, suggesting that CNCHO is spatially extended and not concentrated toward the Sgr B2(N-LMH) position. Moreover, with a GBT beamwidth of ~350^{' '}, the 5(1, 5)-6(0, 6) transition of CNCHO was detected in absorption, confirming the widespread spatial extent of this molecule. We suggest that cyanoformaldehyde is likely formed in a neutral-radical reaction of two other interstellar molecules known for widespread spatial distributions: formaldehyde (H₂CO) and the cyanide (CN) radical.