The bound origin of low-mass stellar binaries

Abstract

Most main sequence stars, unlike our Sun, belong to multiple systems with two or more stars. How and when these multiples come together and become bound is uncertain, since the earliest stages of star formation are difficult to resolve. We analyze simulations of star cluster formation in Milky Way-like conditions, including all key physics and stellar feedback mechanisms, to understand how multiple systems form. We show that $\approx 70-80\%$ of binaries are gravitationally bound from the moment the second star forms. Binaries evolve and accrete together, which will affect their planetary systems and chemical evolution. Half of the binaries are disrupted by the end of the star-formation epoch, such that $\approx 40\%$ of the final single stars belonged to a multiple at some point, with implications for the stellar initial mass function. Formation in multiples is the dominant mode of star formation, accounting for at least 57% of stars.

Main text: 11 pages, 5 figures. 5 extended data figures. 2 supplementary figures. Published in Nature Astronomy Oct 15 2025

References in corpus (48)

• On the variation of the Initial Mass Function
• Binary interaction dominates the evolution of massive stars
• Stellar Multiplicity
• Transient Events from Neutron Star Mergers
• Mind your Ps and Qs: the Interrelation between Period (P) and Mass-ratio (Q) Distributions of Binary Stars
• The Stellar IMF from Turbulent Fragmentation
• Modelling Accretion in Protobinary Systems
• Density, Velocity, and Magnetic Field Structure in Turbulent Molecular Cloud Models
• The Formation of a Star Cluster: Predicting the Properties of Stars and Brown Dwarfs
• Black hole mergers in the universe
• Stellar, brown dwarf and multiple star properties from a radiation hydrodynamical simulation of star cluster formation
• Stellar, Brown Dwarf, and Multiple Star Properties from Hydrodynamical Simulations of Star Cluster Formation
• The Effects of Radiative Transfer on Low-Mass Star Formation
• The Formation of Stellar Clusters: Gaussian Cloud Conditions I
• The Formation of Low-Mass Binary Star Systems Via Turbulent Fragmentation
• Predicting the Properties of Binary Stellar Systems: The Evolution of Accreting Protobinary Systems
• The Solar Neighborhood XLV. The Stellar Multiplicity Rate of M Dwarfs Within 25 pc
• Radiation-Hydrodynamic Simulations of the Formation of Orion-Like Star Clusters II. The Initial Mass Function from Winds, Turbulence, and Radiation
• STARFORGE: Toward a comprehensive numerical model of star cluster formation and feedback
• Accurate, Meshless Methods for Magneto-Hydrodynamics
• The Origin of Massive Stars: The Inertial-Inflow Model
• The Spatial Structure of Young Stellar Clusters. I. Subclusters
• The dynamics and outcome of star formation with jets, radiation, winds, and supernovae in concert
• Formation of close binaries by disc fragmentation and migration, and its statistical modeling
• Dynamical Formation of Close Binaries During the Pre-main-sequence Phase
• Impact of Binary Stars on Planet Statistics -- I. Planet Occurrence Rates, Trends with Stellar Mass, and Wide Companions to Hot Jupiter Hosts
• The molecular cloud lifecycle
• The Origin and Universality of the Stellar Initial Mass Function
• A model for the formation of stellar associations and clusters from giant molecular clouds
• Not all stars form in clusters -- $Gaia$-DR2 uncovers the origin of OB associations
• How to build Tatooine: reducing secular excitation in Kepler circumbinary planet formation
• Effects of the environment and feedback physics on the initial mass function of stars in the STARFORGE simulations
• Generalized Hill-Stability Criteria for Hierarchical Three-Body Systems at Arbitrary Inclinations
• The Formation and Evolution of Wide-Orbit Stellar Multiples In Magnetized Clouds
• The Bridge: a transient phenomenon of forming stellar multiples
• Unbound Young Stellar Systems: Star Formation on the loose
• The Formation of Stellar Clusters in Magnetized, Filamentary Infrared Dark Clouds
• The Evolution of Protostars: Insights from Ten Years of Infrared Surveys with Spitzer and Herschel
• Runaway Stars and the Escape of Ionizing Radiation from High-Redshift Galaxies
• An Observed Lack of Substructure in Starless Cores
• Evidence for Environmentally Dependent Cluster Disruption in M83
• The Mass-Size Relation and the Constancy of GMC Surface Densities in the Milky Way
• Binary formation through gas-assisted capture and the implications for stellar, planetary and compact-object evolution
• Protostellar half-life: new methodology and estimates
• Implementing Primordial Binaries in Simulations of Star Cluster Formation with a Hybrid MHD and Direct N-Body Method
• Protostellar Feedback in Turbulent Fragmentation: Consequences for Stellar Clustering and Multiplicity
• Effects of the environment on the multiplicity properties of stars in the STARFORGE simulations
• The contribution of binary star formation via core-fragmentation on protostellar multiplicity

Cited by in corpus (1)

• Formation of massive multiple-star systems: early migration and mergers