Formation of Be stars via wind accretion: Case study on Black Hole + Be star binaries
Li Z, Jia S, Wei D, Ge H, Chen H, Zhang Y, Chen X, Han Z. 2026. Formation of Be stars via wind accretion: Case study on Black Hole + Be star binaries. The Astrophysical Journal Letters. 996(2), L42.
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Author
Li, Zhenwei;
Jia, Shi;
Wei, DandanISTA;
Ge, Hongwei;
Chen, Hailiang;
Zhang, Yangyang;
Chen, Xuefei;
Han, Zhanwen
Department
Abstract
Be stars are rapidly rotating main-sequence stars that play a crucial role in understanding stellar evolution and binary interactions. In this Letter, we propose a new formation scenario for black hole (BH) + Be star binaries (hereafter BHBe binaries), where the Be star is produced through the wind Roche lobe overflow (WRLOF) mechanism. Our analysis is based on numerical simulations of the WRLOF process in massive binaries, building on recent theoretical work. We demonstrate that the WRLOF model can efficiently form BHBe binaries under reasonable assumptions on stellar wind velocities. Using rapid binary population synthesis, we estimate the population of such systems in the Milky Way, predicting ∼1800−3200 currently existing BHBe binaries originating from the WRLOF channel. These systems are characterized by high eccentricities and exceptionally wide orbits, with typical orbital periods exceeding 1000 days and a peak distribution around ∼10,000 days. Due to their long orbital separations, these BHBe binaries are promising targets for future detection via astrometric and interferometric observations.
Publishing Year
Date Published
2026-01-10
Journal Title
The Astrophysical Journal Letters
Publisher
IOP Publishing
Acknowledgement
We are deeply grateful to the anonymous referee for the insightful comments, which have significantly improved the quality of this work. The authors express their gratitude to Zhaoyu Zuo and I. El Mellah for sharing the grids of wind accretion efficiencies. Z.L. thanks Matthias U. Kruckow for detailed discussions about the BH formation. This work is supported by the Natural Science Foundation of China (grant Nos. 12125303, 12525304, 12288102, 12090040/3, 12473034, 12503044, 12333008, 12433009, 12422305, 12273105, 12073070, 12173081), the Strategic Priority Research Program of the Chinese Academy of Sciences (grant Nos. XDB1160303, XDB1160201, XDB1160000), the National Key R&D Program of China (grant Nos. 2021YFA1600403 and 2021YFA1600400), the CAS “Light of West China,” the Yunnan Revitalization Talent Support Program-Science & Technology Champion Project (No. 202305AB350003) and Young Talent project, the International Centre of Supernovae (ICESUN), Yunnan Key Laboratory of Supernova Research (Nos. 202302AN360001 and 202201BC070003), Yunnan Fundamental Research Projects (No. 202401AT070139), and the Natural Science Foundation of Henan Province (No. 242300420944). X.C. acknowledges the New Cornerstone Science Foundation through the XPLORER PRIZE. The authors gratefully acknowledge the “PHOENIX Supercomputing Platform” jointly operated by the Binary Population Synthesis Group and the Stellar Astrophysics Group at Yunnan Observatories, Chinese Academy of Sciences.
Volume
996
Issue
2
Article Number
L42
ISSN
eISSN
IST-REx-ID
Cite this
Li Z, Jia S, Wei D, et al. Formation of Be stars via wind accretion: Case study on Black Hole + Be star binaries. The Astrophysical Journal Letters. 2026;996(2). doi:10.3847/2041-8213/ae3008
Li, Z., Jia, S., Wei, D., Ge, H., Chen, H., Zhang, Y., … Han, Z. (2026). Formation of Be stars via wind accretion: Case study on Black Hole + Be star binaries. The Astrophysical Journal Letters. IOP Publishing. https://doi.org/10.3847/2041-8213/ae3008
Li, Zhenwei, Shi Jia, Dandan Wei, Hongwei Ge, Hailiang Chen, Yangyang Zhang, Xuefei Chen, and Zhanwen Han. “Formation of Be Stars via Wind Accretion: Case Study on Black Hole + Be Star Binaries.” The Astrophysical Journal Letters. IOP Publishing, 2026. https://doi.org/10.3847/2041-8213/ae3008.
Z. Li et al., “Formation of Be stars via wind accretion: Case study on Black Hole + Be star binaries,” The Astrophysical Journal Letters, vol. 996, no. 2. IOP Publishing, 2026.
Li Z, Jia S, Wei D, Ge H, Chen H, Zhang Y, Chen X, Han Z. 2026. Formation of Be stars via wind accretion: Case study on Black Hole + Be star binaries. The Astrophysical Journal Letters. 996(2), L42.
Li, Zhenwei, et al. “Formation of Be Stars via Wind Accretion: Case Study on Black Hole + Be Star Binaries.” The Astrophysical Journal Letters, vol. 996, no. 2, L42, IOP Publishing, 2026, doi:10.3847/2041-8213/ae3008.
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