The non-monotonic, strong metallicity dependence of the wide-binary fraction

Abstract

The metallicity dependence of the wide-binary fraction in stellar populations plays a critical role in resolving the open question of wide binary formation. In this paper, we investigate the metallicity ([Fe/H]) and age dependence of the wide-binary fraction (binary separations between $10^3$ and $10^4$ AU) for field F and G dwarfs within 500 pc by combining their metallicity and radial velocity measurements from LAMOST DR5 with the astrometric information from Gaia DR2. We show that the wide-binary fraction strongly depends on the metallicity: as metallicity increases, the wide-binary fraction first increases, peaks at [Fe/H]$\simeq 0$, and then decreases at the high metallicity end. The wide-binary fraction at [Fe/H]$=0$ is about two times larger than that at [Fe/H]$=-1$ and [Fe/H]$=+0.5$. This metallicity dependence is dominated by the thin-disk stars. Using stellar kinematics as a proxy of stellar age, we show that younger stars have a higher wide-binary fraction at fixed metallicity close to solar. We propose that multiple formation channels are responsible for the metallicity and age dependence. In particular, the positive metallicity correlation at [Fe/H]$<0$ and the age dependence may be due to the denser formation environments and higher-mass clusters at earlier times. The negative metallicity correlation at [Fe/H]$>0$ can be inherited from the similar metallicity dependence of close binaries, and radial migration may play a role in enhancing the wide-binary fraction around the solar metallicity.

Accepted by MNRAS. Fig 3 and 7 are the key results

References in corpus (39)

• The Gaia mission
• galpy: A Python Library for Galactic Dynamics
• Trigonometric Parallaxes of Massive Star Forming Regions: VI. Galactic Structure, Fundamental Parameters and Non-Circular Motions
• New constraints on the chemical evolution of the solar neighbourhood and Galactic disc(s). Improved astrophysical parameters for the Geneva-Copenhagen Survey
• The GALAH Survey: Scientific Motivation
• Tertiary companions to close spectroscopic binaries
• Gaia Data Release 1: Catalogue validation
• Gas expulsion and the destruction of massive young clusters
• Unresolved stellar companions with Gaia DR2 astrometry
• Contact Binaries with Additional Components.I. The Extant Data
• A Triple Protostar System Formed via Fragmentation of a Gravitationally Unstable Disk
• Fragmentation of Massive Protostellar Disks
• Formation of close binaries by disc fragmentation and migration, and its statistical modeling
• On the Reported Death of the MACHO Era
• Kinematic modelling of the Milky Way using the RAVE and GCS stellar surveys
• The statistical properties of stars and their dependence on metallicity
• The statistical properties of stars and their dependence on metallicity: the effects of opacity
• Keeping it Cool: Much Orbit Migration, yet Little Heating, in the Galactic Disk
• Identical or fraternal twins? : The chemical homogeneity of wide binaries from Gaia DR2
• The Rich Are Different: Evidence from the RAVE Survey for Stellar Radial Migration
• Early turbulent mixing as the origin of chemical homogeneity in open star clusters
• A catalog of wide binary and multiple systems of bright stars from Gaia-DR2 and the Virtual Observatory
• Wide binaries are rare in open clusters
• The Close Binary Fraction as a Function of Stellar Parameters in APOGEE: A Strong Anti-Correlation With $\alpha$ Abundances
• Stellar loci II. a model-free estimate of the binary fraction for field FGK stars
• Measuring 14 elemental abundances with R=1,800 LAMOST spectra
• Prospects for Measuring Abundances of >20 Elements with Low-resolution Stellar Spectra
• Multiplicity and clustering in Taurus star-forming region. I. Unexpected ultra-wide pairs of high-order multiplicity in Taurus
• Eccentricity distribution of wide low-mass binaries
• Formation of Wide Binaries by Turbulent Fragmentation
• Wide Binaries in Tycho-Gaia II: Metallicities, Abundances, and Prospects for Chemical Tagging
• Constraints on Radial Migration in Spiral Galaxies - II. Angular momentum distribution and preferential migration
• Cool Subdwarf Investigations II: Multiplicity
• The Metallicity of Stars with Close Companions
• Very wide companion fraction from Gaia DR2: a weak or no enhancement for hot jupiter hosts, and a strong enhancement for contact binaries
• The GALAH Survey: Temporal Chemical Enrichment of the Galactic Disk
• Multiplicity of the Galactic Senior Citizens: A high-resolution search for cool subdwarf companions
• The Rich Lack Close Neighbours: The Dependence of Blue-Straggler Fraction on Metallicity
• Insights into the Formation and Evolution History of the Galactic Disk System

Cited by in corpus (22)

• A million binaries from Gaia eDR3: sample selection and validation of Gaia parallax uncertainties
• Overview of the LAMOST survey in the first decade
• Binary Stars in the New Millennium
• Wide twin binaries are extremely eccentric: evidence of twin binary formation in circumbinary disks
• Close Encounters of Wide Binaries Induced by the Galactic Tide: Implications for Stellar Mergers and Gravitational-Wave Sources
• 10,000 Resolved Triples from Gaia: Empirical Constraints on Triple Star Populations
• The mystery in Gaia DR3 triples: occurrence rates, orientations, and eccentricities of wide tertiaries around close binaries
• Binary fractions of G and K dwarf stars based on the Gaia EDR3 and LAMOST DR5: impacts of the chemical abundances
• On the phase-mixed eccentricity and inclination distributions of wide binaries in the Galaxy
• Radio Loud vs. Radio Quiet Gamma-ray Bursts: the Role of Binary Progenitors
• Enhancement of Double-Close-Binary Quadruples
• Wide binary stars formed in the turbulent interstellar medium
• A Statistical Detection of Wide Binary Systems in the Ultra-Faint Dwarf Galaxy Reticulum II
• Wide binaries from the H3 survey: the thick disk and halo have similar wide binary fractions
• Vetting the Lobster Diagram: Searching for Unseen Companions in Wide Binaries using NASA Space Exoplanet Missions
• Dynamical masses across the Hertzsprung-Russell diagram
• Chemodynamics of metal-poor wide binaries in the Galactic halo: Association with the Sequoia event
• The Low-Mass Stellar Initial Mass Function in Nearby Ultrafaint Dwarf Galaxies
• Not that simple: the metallicity dependence of the wide binary fraction changes with separation and stellar mass
• Stellar masses and mass ratios for Gaia open cluster members
• The eccentricity distribution of wide binaries and their individual measurements
• Stellar Multiplicity in Open Clusters: Investigating Binary Fractions and Their Relationship with Cluster Properties