Magnetic Signatures in Merger Products
Abstract
Asteroseismic estimates of the magnetic field strength in the radiative interior of red giant stars depend strongly on the internal stellar structure derived from models. Since red giant branch merger products have been shown to be able to possess a different core structure than single stars of the same mass, we investigate how a mass-gain history influences our estimates of an internal magnetic field strength. We construct stellar models with and without a mass-gain event after the onset of the RGB evolutionary phase with masses of 1.1 M⊙ ≤ M ≤ 2 M⊙. First, by assuming a weak magnetic field, we investigate the influence of a mass-gain event on the global sensitivity of the oscillation frequencies to the magnetic field. We find that mass-gain models can be several times more sensitive to the field than single-star models of identical total mass at masses above 1.6 M⊙. Therefore, considering a mass-gain evolutionary history for merger candidates allows a significant correction to the magnetic field strength. In the presence of strong magnetic fields, we also show that the critical field strength needed to suppress mixed dipole modes is significantly lower if a mass-gain event has occurred (for stars with masses M≳1.6 M⊙). The massive end of the suppressed stars' distribution is therefore strongly favored by a merger origin. We conclude that properly constraining the stellar evolutionary history is essential when aiming to constrain internal field strength estimates from asteroseismic observations.
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BibTeX
@misc{muntean2026magnetic,
title = {{Magnetic Signatures in Merger Products}},
author = {Nicolas Muntean and Lisa Bugnet and Lynn Buchele and Debasish Dutta and Lukas Einramhof and Paul G. Beck and Lucas Barrault and Bastien Liagre},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.08466},
eprint = {2609.08466},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.08466},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Magnetic Signatures in Merger Products
AU - Nicolas Muntean
AU - Lisa Bugnet
AU - Lynn Buchele
AU - Debasish Dutta
AU - Lukas Einramhof
AU - Paul G. Beck
AU - Lucas Barrault
AU - Bastien Liagre
PY - 2026
DA - 2026/09/08
PB - arXiv
DO - 10.48550/arxiv.2609.08466
UR - https://arxiv.org/abs/2609.08466
AB - Asteroseismic estimates of the magnetic field strength in the radiative interior of red giant stars depend strongly on the internal stellar structure derived from models. Since red giant branch merger products have been shown to be able to possess a different core structure than single stars of the same mass, we investigate how a mass-gain history influences our estimates of an internal magnetic field strength. We construct stellar models with and without a mass-gain event after the onset of the RGB evolutionary phase with masses of 1.1 M_⊙ ≤ M ≤ 2 M_⊙. First, by assuming a weak magnetic field, we investigate the influence of a mass-gain event on the global sensitivity of the oscillation frequencies to the magnetic field. We find that mass-gain models can be several times more sensitive to the field than single-star models of identical total mass at masses above 1.6 M_⊙. Therefore, considering a mass-gain evolutionary history for merger candidates allows a significant correction to the magnetic field strength. In the presence of strong magnetic fields, we also show that the critical field strength needed to suppress mixed dipole modes is significantly lower if a mass-gain event has occurred (for stars with masses M≳1.6 M_⊙). The massive end of the suppressed stars' distribution is therefore strongly favored by a merger origin. We conclude that properly constraining the stellar evolutionary history is essential when aiming to constrain internal field strength estimates from asteroseismic observations.
ER -