Wide binary stars formed in the turbulent interstellar medium

Abstract

The ubiquitous interstellar turbulence regulates star formation and the scaling relations between the initial velocity differences and the initial separations of stars. We propose that the formation of wide binaries with initial separations $r$ in the range $\sim 10^3\text{AU}\lesssim r\lesssim 10^5$ AU is a natural consequence of star formation in the turbulent interstellar medium. With the decrease of $r$, the mean turbulent relative velocity $v_{\text{tur}}$ between a pair of stars decreases, while the largest velocity $v_{\text{bon}}$ at which they still may be gravitationally bound increases. When $v_{\text{tur}}<v_{\text{bon}}$, a wide binary can form. In this formation scenario, we derive the eccentricity distribution $p(e)$ of wide binaries for an arbitrary relative velocity distribution. By adopting a turbulent velocity distribution, we find that wide binaries at a given initial separation generally exhibit a superthermal $p(e)$. This provides a natural explanation for the observed superthermal $p(e)$ of the wide binaries in the Solar neighborhood.

7 pages, 4 figures, submitted to ApJL

References in corpus (27)

• Theory of Star Formation
• Gaia Data Release 1. Summary of the astrometric, photometric, and survey properties
• A million binaries from Gaia eDR3: sample selection and validation of Gaia parallax uncertainties
• Lidov-Kozai Cycles with Gravitational Radiation: Merging Black Holes in Isolated Triple Systems
• The Fractal Density Structure in Supersonic Isothermal Turbulence: Solenoidal versus Compressive Energy Injection
• The end of the MACHO era- revisited: new limits on MACHO masses from halo wide binaries
• The sonic scale revealed by the world's largest supersonic turbulence simulation
• On the Reported Death of the MACHO Era
• The statistical properties of stars and their dependence on metallicity: the effects of opacity
• Gaia EDR3 Reveals the Substructure and Complicated Star Formation History of the Greater Taurus-Auriga Star Forming Complex
• Identical or fraternal twins? : The chemical homogeneity of wide binaries from Gaia DR2
• The structure and statistics of interstellar turbulence
• Wide binaries are rare in open clusters
• Scatter broadening of pulsars and implications on the interstellar medium turbulence
• The IMF and multiplicity of stars from gravity, turbulence, magnetic fields, radiation and outflow feedback
• Measuring Turbulence with Young Stars in the Orion Complex
• Turbulence in a self-gravitating molecular cloud core
• Wide binary companions to massive stars and their use in constraining natal kicks
• The Velocity Statistics of Turbulent Clouds in the Presence of Gravity, Magnetic fields, Radiation, and Outflow Feedback
• Measuring magnetization with rotation measures and velocity centroids in supersonic MHD turbulence
• Nonuniversal interstellar density spectra probed by pulsars
• Very wide companion fraction from Gaia DR2: a weak or no enhancement for hot jupiter hosts, and a strong enhancement for contact binaries
• The mystery in Gaia DR3 triples: occurrence rates, orientations, and eccentricities of wide tertiaries around close binaries
• Projected velocity statistics of interstellar turbulence
• On the phase-mixed eccentricity and inclination distributions of wide binaries in the Galaxy
• Solenoidal turbulent modes and star formation efficiency in Galactic-plane molecular clouds
• Evolution of binary stars in the early evolutionary phases of ultra-faint dwarf galaxies