Be Star Formation through Stellar Mergers: V1371 Tau
- 1University of Nevada
Abstract
The origin of the near-critical rotation of classical Be stars remains uncertain. Binary mass transfer provides a formation channel, but it cannot explain Be stars that are observed without a close companion. We investigate V1371 Tau, a hierarchical triple containing an inner B+B binary and an outer Be star. With n -body simulations, we first show that the observed inclination variations of the B+B binary do not require von Zeipel–Lidov–Kozai (ZLK) oscillations, as nodal precession alone can produce substantial changes in inclination relative to the line of sight. We then consider whether V1371 Tau formed from a primordial 2+2 quadruple, in which a progenitor binary of the Be star underwent ZLK-driven eccentricity excitation and merged. We find that mergers occur over a broad range of progenitor binary parameters while leaving the observed B+B binary intact. The merger remnant is expected to retain the orbital angular-momentum direction at the time of merger, producing a potentially observable misalignment between the Be-star spin axis and its orbit around the surviving B+B binary. These results demonstrate that ZLK-driven mergers in higher-order multiple systems provide a viable formation pathway for rapidly rotating Be stars without present-day close companions.
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BibTeX
@article{martin2026star,
title = {{Be Star Formation through Stellar Mergers: V1371 Tau}},
author = {Rebecca G. Martin and Peter Quigley and Stephen Lepp},
journal = {The Astrophysical Journal Letters},
year = {2026},
month = oct,
doi = {10.3847/2041-8213/aeacbf},
url = {https://iopscience.iop.org/article/10.3847/2041-8213/aeacbf},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Be Star Formation through Stellar Mergers: V1371 Tau
AU - Rebecca G. Martin
AU - Peter Quigley
AU - Stephen Lepp
PY - 2026
DA - 2026/10/22
JO - The Astrophysical Journal Letters
DO - 10.3847/2041-8213/aeacbf
UR - https://iopscience.iop.org/article/10.3847/2041-8213/aeacbf
AB - The origin of the near-critical rotation of classical Be stars remains uncertain. Binary mass transfer provides a formation channel, but it cannot explain Be stars that are observed without a close companion. We investigate V1371 Tau, a hierarchical triple containing an inner B+B binary and an outer Be star. With n -body simulations, we first show that the observed inclination variations of the B+B binary do not require von Zeipel–Lidov–Kozai (ZLK) oscillations, as nodal precession alone can produce substantial changes in inclination relative to the line of sight. We then consider whether V1371 Tau formed from a primordial 2+2 quadruple, in which a progenitor binary of the Be star underwent ZLK-driven eccentricity excitation and merged. We find that mergers occur over a broad range of progenitor binary parameters while leaving the observed B+B binary intact. The merger remnant is expected to retain the orbital angular-momentum direction at the time of merger, producing a potentially observable misalignment between the Be-star spin axis and its orbit around the surviving B+B binary. These results demonstrate that ZLK-driven mergers in higher-order multiple systems provide a viable formation pathway for rapidly rotating Be stars without present-day close companions.
SN - 2041-8205
SN - 2041-8213
ER -