A Million Three-body Binaries Caught by Gaia

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Main Authors: Atallah, Dany, Ginat, Yonadav Barry, Weatherford, Newlin C.
Format: Preprint
Published: 2025
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author Atallah, Dany
Ginat, Yonadav Barry
Weatherford, Newlin C.
author_facet Atallah, Dany
Ginat, Yonadav Barry
Weatherford, Newlin C.
contents Gaia observations have revealed over a million stellar binary candidates within ~1 kpc of the Sun, predominantly characterized by orbital separations >10^3 AU and eccentricities >0.7. The prevalence of such wide, eccentric binaries has proven challenging to explain through canonical binary formation channels. However, recent advances in our understanding of three-body binary formation (3BBF) -- new binary assembly by the gravitational scattering of three unbound bodies (3UB) -- have shown that 3BBF in star clusters can efficiently generate wide, highly eccentric binaries. We further explore this possibility by constructing a semi-analytic model of the Galactic binary population in the solar neighborhood, originating from 3BBF in star clusters and subsequently migrating to the solar neighborhood within a Hubble time. The model relies on 3BBF scattering experiments to determine how the 3BBF rate and resulting binary properties scale with local stellar density, velocity dispersion, and physically-motivated limits to 3UB encounters within a clusters' tidal field. The Galactic star cluster population is modeled by incorporating up-to-date prescriptions for the Galaxy's star formation history as well as the birth properties and internal evolution of its star clusters. Finally, we account for binary disruption induced by perturbations from stellar interactions before cluster dissolution and the subsequent changes and disruption of binary orbital elements induced by dynamical interactions in the Galactic field. Our model closely reproduces the total number of Gaia's wide binaries and the separation and eccentricity distributions, suggesting that 3BBF may be an important formation channel for these enigmatic systems.
format Preprint
id arxiv_https___arxiv_org_abs_2503_14605
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle A Million Three-body Binaries Caught by Gaia
Atallah, Dany
Ginat, Yonadav Barry
Weatherford, Newlin C.
Astrophysics of Galaxies
Gaia observations have revealed over a million stellar binary candidates within ~1 kpc of the Sun, predominantly characterized by orbital separations >10^3 AU and eccentricities >0.7. The prevalence of such wide, eccentric binaries has proven challenging to explain through canonical binary formation channels. However, recent advances in our understanding of three-body binary formation (3BBF) -- new binary assembly by the gravitational scattering of three unbound bodies (3UB) -- have shown that 3BBF in star clusters can efficiently generate wide, highly eccentric binaries. We further explore this possibility by constructing a semi-analytic model of the Galactic binary population in the solar neighborhood, originating from 3BBF in star clusters and subsequently migrating to the solar neighborhood within a Hubble time. The model relies on 3BBF scattering experiments to determine how the 3BBF rate and resulting binary properties scale with local stellar density, velocity dispersion, and physically-motivated limits to 3UB encounters within a clusters' tidal field. The Galactic star cluster population is modeled by incorporating up-to-date prescriptions for the Galaxy's star formation history as well as the birth properties and internal evolution of its star clusters. Finally, we account for binary disruption induced by perturbations from stellar interactions before cluster dissolution and the subsequent changes and disruption of binary orbital elements induced by dynamical interactions in the Galactic field. Our model closely reproduces the total number of Gaia's wide binaries and the separation and eccentricity distributions, suggesting that 3BBF may be an important formation channel for these enigmatic systems.
title A Million Three-body Binaries Caught by Gaia
topic Astrophysics of Galaxies
url https://arxiv.org/abs/2503.14605