2017ApJ...849..139Z

We present observations of interstellar acetone (CH₃COCH₃) detected in broadband line surveys in the 1.3 mm band from the Caltech Submillimeter Observatory (CSO). The observations were conducted toward three massive star-forming regions: GAL 31.41+0.31, GAL 034.3+00.2, and GAL 10.47+00.03. Numerous acetone lines were detected in these three sources. The results were analyzed using the assumption of local thermodynamic equilibrium. These results rigorously confirm the previous reports of acetone detections in GAL 31.41+0.31 and GAL 10.47+00.03, and add a new acetone detection in GAL 034.3+00.2. Source-averaged column densities for acetone were determined to be 1.1(6)×10¹⁶ cm^–2 for GAL 31.41+0.31, 6.4(3)×10¹⁶ cm^–2 for GAL 10.47+00.03, and 1.3(3)×10¹⁵ cm^–2 for GAL 034.3+00.2. The rotational temperatures of acetone in these three sources range from 49 to 132 K, which suggests a complicated formation mechanism for interstellar acetone.