Observations and radiative transfer modelling of a massive dense cold core in G333

TL;DR

This study combines multi-wavelength observations and 3D radiative transfer modelling to analyze a cold, dense core in G333, revealing its structure, chemistry, and early star formation activity.

Contribution

It provides a detailed physical and chemical characterization of G333.125-0.562 using new observational data and advanced 3D line transfer modelling, highlighting its early evolutionary stage.

Findings

Core consists of two sources with different evolutionary stages.

Heavy depletion of CO isotopes due to freeze-out onto dust grains.

Presence of a central driving source with an outflow.

Abstract

Cold massive cores are one of the earliest manifestations of high mass star formation. Following the detection of SiO emission from G333.125-0.562, a cold massive core, further investigations of the physics, chemistry and dynamics of this object has been carried out. Mopra and NANTEN2 molecular line profile observations, Australia Telescope Compact Array (ATCA) line and continuum emission maps, and Spitzer 24 and 70 \mum images were obtained. These new data further constrain the properties of this prime example of the very early stages of high mass star formation. A model for the source was constructed and compared directly with the molecular line data using a 3D molecular line transfer code - MOLLIE. The ATCA data reveal that G333.125-0.562 is composed of two sources. One of the sources is responsible for the previously detected molecular outflow and is detected in the Spitzer 24 and 70 \mum band data. Turbulent velocity widths are lower than other more active regions of G333 which reflects the younger evolutionary stage and/or lower mass of this core. The molecular line modelling requires abundances of the CO isotopes that strongly imply heavy depletion due to freeze-out of this species onto dust grains. The principal cloud is cold, moderately turbulent and possesses an outflow which indicates the presence of a central driving source. The secondary source could be an even less evolved object as no apparent associations with continuum emissions at (far-)infrared wavelengths.