Can the Anomalous Magnetic Braking of Ap/Bp Stars Explain the Orbital Decay of Algol-type Binaries?
Year: 2025
Type: article
Abstract: Several Algol-type binaries were detected to be experiencing rapid orbital decay, which is in contradiction with the conservative mass transfer model. In this work, we investigate whether anomalous magnetic braking (MB) of intermediate-mass Ap/Bp stars, characterized by surface magnetic fields of ∼102–104 G, could drive orbital decay through magnetic wind–field coupling. Using the stellar evolution code MESA, we simulate the evolution of several main-sequence binaries containing Ap/Bp stars, with typical initial parameters of Algol binaries. Our models indicate that the anomalous MB mechanism could induce orbital decay in long timescales (hundreds of Myr to several Gyr), reproducing several basic Algol parameters such as the effective temperatures and luminosities of donor stars. However, the predicted orbital period decay rates are much lower than those observed in several Algol systems. We analyze the limitations of the anomalous MB model and discuss alternative mechanisms that could account for the long- or short-term orbital period variations observed in Algol systems, including a surrounding circumbinary disk, stellar expansion, the Applegate mechanism, and the light-travel-time effect. Long-term observations are still required to distinguish between these mechanisms in the future.
Source: The Astrophysical Journal
Authors: Guan-Long Wu, Zhao-Yu Zuo, Wen-Cong Chen
Institutions: Xi'an Jiaotong University, Qingdao University of Technology
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $4,499
Award: G3167614697
OpenAlex ID: W4414999953