Multi-scale dynamics in star-forming regions: the interplay between gravity and turbulence

TL;DR

This paper investigates the multi-scale dynamics of star-forming regions, revealing how turbulence initially shapes structures and gravity dominates at higher densities, leading to collapse and star formation.

Contribution

It combines observational data of clumps and filaments to identify the scale-dependent interplay between turbulence and gravity in star formation.

Findings

Turbulence creates structures at all scales.

Gravity becomes dominant at a critical surface density.

Global collapse occurs in dense filaments, leading to massive star formation.

Abstract

In the multi-scale view of the star formation process the material flows from large molecular clouds down to clumps and cores. In this paradigm it is still unclear if it is gravity or turbulence that drives the observed supersonic non-thermal motions during the collapse, in particular in high-mass regions, and at which scales gravity becomes eventually dominant over the turbulence of the interstellar medium. To investigate this problem we have combined the dynamics of a sample of 70 micron-quiet clumps, selected to cover a wide range of masses and surface densities, with the dynamics of the parent filaments in which they are embedded. We observe a continuous interplay between turbulence and gravity, where the former creates structures at all scales and the latter takes the lead when a critical value of the surface density is reached, Sigma_th = 0.1 g cm^-2. In the densest filaments this transition can occur at the parsec, or even larger scales, leading to a global collapse of the whole region and most likely to the formation of the massive objects.