Fates of the sub-stellar objects (FOSSO) I. Fates of the known brown dwarfs in main-sequence--BD binaries

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Main Authors: Chen, Zhangliang, Jin, Hongming, Ge, Hongwei, Yu, Cong, Wang, Kejun, Chen, Dichang, Ma, Bo
Format: Preprint
Published: 2026
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author Chen, Zhangliang
Jin, Hongming
Ge, Hongwei
Yu, Cong
Wang, Kejun
Chen, Dichang
Ma, Bo
author_facet Chen, Zhangliang
Jin, Hongming
Ge, Hongwei
Yu, Cong
Wang, Kejun
Chen, Dichang
Ma, Bo
contents Context. Understanding the survival and orbital evolution of brown dwarf (BD) companions during the post-main-sequence (MS) evolution of their host stars is increasingly important, especially with recent discoveries of many substellar companions around white dwarfs (WDs). Aims. We investigate the long-term evolution and final outcomes of BDs orbiting low-mass MS stars as these evolve into WDs. By comparing forward-modeling populations with observed WD-BD binaries, we test evolutionary models and predict the existence of yet-undetected systems. Methods. We employ the COMPAS binary population synthesis code to evolve observed MS-BD systems through the post-MS phases of their host stars into the WD stage, tracking orbital changes driven by mass loss, tides, and common-envelope (CE) evolution. Results. Our simulations reproduce a period gap in the distribution of detached WD-BD binaries, consistent with observations. We also identify a boundary separating detached and semi-detached systems on the period-mass diagram, located at orbital periods of $\sim$1-2 hours depending on the BD mass. Conclusions. We predict that a subset of currently known MS-BD binaries will survive post-MS evolution and emerge as detached WD-BD systems, while others will undergo CE evolution and potentially form cataclysmic variables with BD donors. Our results reproduce the observed period gap in WD-BD binaries and provide quantitative predictions for the role of CE efficiency in shaping their distribution. This work predicts that many WD-BD systems remain undetected, motivating targeted searches with microlensing and high-contrast imaging techniques using next-generation large telescopes.
format Preprint
id arxiv_https___arxiv_org_abs_2601_12861
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Fates of the sub-stellar objects (FOSSO) I. Fates of the known brown dwarfs in main-sequence--BD binaries
Chen, Zhangliang
Jin, Hongming
Ge, Hongwei
Yu, Cong
Wang, Kejun
Chen, Dichang
Ma, Bo
Solar and Stellar Astrophysics
Earth and Planetary Astrophysics
Context. Understanding the survival and orbital evolution of brown dwarf (BD) companions during the post-main-sequence (MS) evolution of their host stars is increasingly important, especially with recent discoveries of many substellar companions around white dwarfs (WDs). Aims. We investigate the long-term evolution and final outcomes of BDs orbiting low-mass MS stars as these evolve into WDs. By comparing forward-modeling populations with observed WD-BD binaries, we test evolutionary models and predict the existence of yet-undetected systems. Methods. We employ the COMPAS binary population synthesis code to evolve observed MS-BD systems through the post-MS phases of their host stars into the WD stage, tracking orbital changes driven by mass loss, tides, and common-envelope (CE) evolution. Results. Our simulations reproduce a period gap in the distribution of detached WD-BD binaries, consistent with observations. We also identify a boundary separating detached and semi-detached systems on the period-mass diagram, located at orbital periods of $\sim$1-2 hours depending on the BD mass. Conclusions. We predict that a subset of currently known MS-BD binaries will survive post-MS evolution and emerge as detached WD-BD systems, while others will undergo CE evolution and potentially form cataclysmic variables with BD donors. Our results reproduce the observed period gap in WD-BD binaries and provide quantitative predictions for the role of CE efficiency in shaping their distribution. This work predicts that many WD-BD systems remain undetected, motivating targeted searches with microlensing and high-contrast imaging techniques using next-generation large telescopes.
title Fates of the sub-stellar objects (FOSSO) I. Fates of the known brown dwarfs in main-sequence--BD binaries
topic Solar and Stellar Astrophysics
Earth and Planetary Astrophysics
url https://arxiv.org/abs/2601.12861