Tracing early evolutionary stages of high-mass star formation with molecular lines

Abstract

Context. Despite its major role in the evolution of the interstellar medium, the formation of high-mass stars (M ≥ 10 M⊙) remains poorly understood. Two types of massive star cluster precursors, the so-called massive dense cores (MDCs), have been observed, which differ in terms of their mid-infrared brightness. The origin of this difference has not yet been established and may be the result of evolution, density, geometry differences, or a combination of these.