Detection of interstellar cyanoformaldehyde (CNCHO)

Cyanoformaldehyde (CNCHO) has been detected toward the star-forming region Sagittarius B-2(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-ij mu(2) > 10 D-2) and occur in spectral regions that have little possibility of confusion with other molecular 2 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 similar to 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.