Microwave detection of interstellar ketene

Abstract

Interstellar ketene (H/sub 2/C=C=O) has been observed in the source Sgr B2 via its transitions 5/sub 14//sub -/4/sub 13/, 5/sub 15//sub -/4/sub 14/, and 4/sub 13//sub -/3/sub 12/ at frequencies 101981.39, 100094.51, and 81586.19 MHz, respectively. The transitions 5/sub 05//sub -/4/sub 04/, 4/sub 14//sub -/3/sub 13/, and 4/sub 04//sub -/3/sub 03/ have also tentatively been detected. Statistical equilibrium calculations suggest a rather low column density for ketene (approx.10/sup 14/ cm/sup -2/) arising from a high-density region (approximately-greater-than10/sup 6/ cm/sup -3/).