2007MNRAS.381L..30L

We report the detection of the SiO (J = 2-1) transition from the massive cold dense core G333.125-0.562. The core remains undetected at wavelengths shorter than 70 µm and has compact 1.2-mm dust continuum. The SiO emission is localized to the core. The observations are part of a continuing multi-molecular line survey of the giant molecular cloud G333. Other detected molecules in the core include ¹³CO, C¹⁸O, CS, HCO⁺, HCN, HNC, CH₃OH, N₂H⁺, SO, HC₃N, NH₃, and some of their isotopes. In addition, from NH₃(1,1) and (2,2) inversion lines, we obtain a temperature of 13 K. From fitting to the spectral energy distribution we obtain a colour temperature of 18 K and a gas mass of 2x10³M_☉. We have also detected a 22-GHz water maser in the core, together with methanol maser emission, suggesting that the core will host massive star formation. We hypothesize that the SiO emission arises from shocks associated with an outflow in the cold core.