2009ApJ...691.1254G

We have surveyed molecular line emission from Orion BN/KL from 42.3 to 43.6 GHz with the Green Bank Telescope. Sixty-seven lines were identified and ascribed to 13 different molecular species. The spectrum at 7 mm is dominated by SiO, SO₂, CH₃OCH₃, and C₂H₅CN. Five transitions have been detected from the SiO isotopologues ²⁸SiO, ²⁹SiO, and ³⁰SiO. We report here for the first time the spectra of the ²⁹SiO and ³⁰SiO v = 0 J = 1-0 emission in Orion BN/KL, and show that they have double-peaked profiles with velocity extents similar to the main isotopologue. The main motivation for the survey was the search of high-velocity (100-1000 km/s) outflows in the BN/KL region as traced by SiO Doppler components. Some of the unidentified lines in principle could be high-velocity SiO features, but without imaging data their location cannot be established. Wings of emission are present in the v = 0 ²⁸SiO, ²⁹SiO, and ³⁰SiO profiles, and we suggest that the v = 0 emission from the three isotopologues might trace a moderately high-velocity (∼30-50 km/s) component of the flows around the high-mass protostar Source I in the Orion BN/KL region. We also confirm the 7 mm detection of a complex oxygen-bearing species, acetone (CH₃COCH₃), which has been recently observed toward the hot core at 3 mm, and have found further indications of the presence of long cyanopolyynes (HC₅ N and HC₇N) in the quiescent cold gas of the extended ridge.