A 42.3-43.6 GHz spectral survey of Orion BN/KL: First detection of the v=0 J=1-0 line from the isotopologues 29SiO and 30SiO

Abstract

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 we 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 towards the hot core at 3 mm, and we have found further indications of the presence of long cyanopolyynes (HC5N and HC7N) in the quiescent cold gas of the extended ridge.