Detection of SiO emission from a massive dense cold core

TL;DR

This study reports the detection of SiO emission from a massive cold dense core, indicating shock activity likely related to outflows, and provides detailed molecular and physical characterization of the core.

Contribution

First detection of SiO emission in a massive cold core, linking it to shock activity and outflows in early star formation stages.

Findings

Detected SiO (J=2-1) emission localized to the core.

Identified multiple molecules indicating complex chemistry.

Presence of water and methanol masers suggests ongoing massive star formation.

Abstract

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 micron and has compact 1.2 mm dust continuum. The SiO emission is localised 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 2 x 10^3 solar mass. We have also detected a 22 GHz water maser in the core, together with methanol maser emission, suggesting the core will host massive star formation. We hypothesise that the SiO emission arises from shocks associated with an outflow in the cold core.