Protostellar Feedback in Turbulent Fragmentation: Consequences for Stellar Clustering and Multiplicity

TL;DR

This paper introduces a semi-analytic model called MISFIT to study how protostellar feedback influences stellar clustering and multiplicity, successfully reproducing observed properties and highlighting the importance of feedback in star formation.

Contribution

The paper presents the MISFIT framework that models gravito-turbulent fragmentation with feedback, providing new insights into stellar clustering and multiplicity.

Findings

Models with feedback match observed multiplicity fractions.

Power-law correlation function on large scales from turbulence and gravity.

Feedback influences the formation of close binaries via disk fragmentation.

Abstract

Stars are strongly clustered on both large (~pc) and small (~binary) scales, but there are few analytic or even semi-analytic theories for the correlation function and multiplicity of stars. In this paper we present such a theory, based on our recently-developed semi-analytic framework called MISFIT, which models gravito-turbulent fragmentation, including the suppression of fragmentation by protostellar radiation feedback. We compare the results including feedback to a control model in which it is omitted. We show that both classes of models robustly reproduce the stellar correlation function at >0.01 pc scales, which is well approximated by a power-law that follows generally from scale-free physics (turbulence plus gravity) on large scales. On smaller scales protostellar disk fragmentation becomes dominant over common core fragmentation, leading to a steepening of the correlation function. Multiplicity is more sensitive to feedback: we found that a model with the protostellar heating reproduces the observed multiplicity fractions and mass ratio distributions for both Solar and sub-Solar mass stars (in particular the brown dwarf desert), while a model without feedback fails to do so. The model with feedback also produces an at-formation period distribution consistent with the one inferred from observations. However, it is unable to produce short-range binaries below the length scale of protostellar disks. We suggest that such close binaries are produced primarily by disk fragmentation and further decrease their separation through orbital decay.