Characterizing the properties of cluster precursors in the MALT90 survey

TL;DR

This study analyzes 1,244 molecular clumps from the MALT90 survey to understand their properties at different evolutionary stages, revealing that less-evolved clumps are denser and more gravitationally bound, with very few resembling young massive cluster progenitors.

Contribution

It provides a comprehensive characterization of the physical properties of cluster-forming clumps at various stages, highlighting the rarity of massive proto-clusters in the Galaxy.

Findings

Less-evolved clumps have lower dust temperatures and higher densities.

Most clumps are not yet massive cluster progenitors.

Very few clumps match properties of young massive cluster precursors.

Abstract

In the Milky Way there are thousands of stellar clusters each harboring from a hundred to a million stars. Although clusters are common, the initial conditions of cluster formation are still not well understood. To determine the processes involved in the formation and evolution of clusters it is key to determine the global properties of cluster-forming clumps in their earliest stages of evolution. Here, we present the physical properties of 1,244 clumps identified from the MALT90 survey. Using the dust temperature of the clumps as a proxy for evolution we determined how the clump properties change at different evolutionary stages. We find that less-evolved clumps exhibiting dust temperatures lower than 20 K have higher densities and are more gravitationally bound than more-evolved clumps with higher dust temperatures. We also identified a sample of clumps in a very early stage of evolution, thus potential candidates for high-mass star-forming clumps. Only one clump in our sample has physical properties consistent with a young massive cluster progenitor, reinforcing the fact that massive proto-clusters are very rare in the Galaxy.