CONFIRMATION OF INTERSTELLAR METHYLENE

Four spectral emission features of the N(KK) = 4(04)-3(13) rotational transition of methylene (CH2) have been detected at signal levels 5-7 sigma above noise toward the hot core of the Orion-KL nebula and the m olecular cloud in proximity to the continuum source W51 M. Specificall y, in both sources we have resolved the F = 6-5, 5-4, and 4-3 hyperfin e transitions of the J = 5-4 fine-structure levels and detected the bl ended hyperfine structure of the J = 4-3 fine structure levels. At the J = 3-2 fine-structure levels, we have observed new transitions of NS , a known interstellar molecule, which severely contaminates the searc h for CH2 hyperfine transitions. These new sensitive observations fina lly confirm the existence of interstellar CH2 which was tentatively re ported by us some years ago.