Gravoturbulent Fragmentation

TL;DR

This paper explores how supersonic turbulence influences star formation in molecular clouds, emphasizing gravoturbulent fragmentation as the key process, and explains observed filamentary structures and star distribution patterns.

Contribution

It introduces the concept of gravoturbulent fragmentation, linking turbulence properties to star formation modes and filament formation, supported by observational and theoretical insights.

Findings

Turbulence determines star formation efficiency and clustering.

Filamentary structures result from compressional flows and shear.

Protostellar distributions align with gravitational fragmentation theory.

Abstract

We discuss star formation in the turbulent interstellar medium. We argue that morphological appearance and dynamical evolution of the gas is primarily determined by supersonic turbulence, and that stars form via a process we call gravoturbulent fragmentation. Turbulence that is dominated by large-scale shocks or is free to decay leads to an efficient, clustered, and synchronized mode of star formation. On the other hand, when turbulence carries most of its energy on very small scales star formation is inefficient and biased towards single objects. The fact that Galactic molecular clouds are highly filamentary can be explained by a combination of compressional flows and shear. Some filaments may accumulate sufficient mass and density to become gravitationally unstable and form stars. This is observed in the Taurus molecular cloud. Timescales and spatial distribution of protostars are well explained by the linear theory of gravitational fragmentation of filaments. The dynamical evolution, especially at late times, and the final mass distribution strongly depend on the global properties of the turbulence. In dense embedded clusters mutual protostellar interactions and competition for the available mass reservoir lead to considerable stochastic variations between the mass growth histories of individual stars.