Detailed study of HD 219134: a benchmark K-dwarf with a compact planetary system
Abstract
Space missions such as CoRoT, Kepler, and TESS have transformed asteroseismology and its synergies with exoplanet science. We revisit the nearby K-dwarf HD 219134 to investigate the tension between asteroseismic and interferometric radii, update its fundamental parameters, and reconstruct the rotational, magnetic, and atmospheric evolution of the system. We combine forward asteroseismic modeling with seismic inversions to assess systematics from non-seismic constraints, radius measurements, and surface modeling. The revised stellar properties are then used for rotational evolution, stellar-wind, and high-energy irradiation calculations. Seismic inversions rule out the most recent interferometric radius, while the asteroseismic and spectroscopic results are compatible with the 2019 interferometric measurement. We obtain M=0.779±0.015(stat)±0.006(sys) M⊙, R=0.753±0.005(stat)±0.002(sys) R⊙, and an age of 8.92±0.89(stat)±0.19(sys) Gyr. These systematics include only non-seismic constraints; literature combined uncertainties from physical inputs and surface effects are 0.007M⊙, 0.002R⊙, and $0.81$ Gyr. Rotational and wind modelling shows that standard magnetic braking is broadly compatible with the present-day rotation and angular-momentum loss. Weakened braking gives a closer match but challenges standard wind-loss scalings. The inferred X-ray history suggests early stripping of the innermost planets, while the outer planets likely retained part of their primordial envelopes; HD 219134d experienced only moderate erosion. The apparent radius discrepancy likely reflects underestimated uncertainties in previous interferometric analyses rather than an astrophysical inconsistency. We advocate adopting the asteroseismic radius, which is robust to modeling assumptions and optimisation strategies.
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BibTeX
@misc{betrisey2026detailed,
title = {{Detailed study of HD 219134: a benchmark K-dwarf with a compact planetary system}},
author = {Jérôme Bétrisey and Camilla Pezzotti and Gaël Buldgen and Aline A. Vidotto and Colin P. Folsom and Michaël De Becker and Michaël Gillon},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.13200},
eprint = {2610.13200},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.13200},
}
RIS
TY - UNPB
TI - Detailed study of HD 219134: a benchmark K-dwarf with a compact planetary system
AU - Jérôme Bétrisey
AU - Camilla Pezzotti
AU - Gaël Buldgen
AU - Aline A. Vidotto
AU - Colin P. Folsom
AU - Michaël De Becker
AU - Michaël Gillon
PY - 2026
DA - 2026/10/09
PB - arXiv
DO - 10.48550/arxiv.2610.13200
UR - https://arxiv.org/abs/2610.13200
AB - Space missions such as CoRoT, Kepler, and TESS have transformed asteroseismology and its synergies with exoplanet science. We revisit the nearby K-dwarf HD 219134 to investigate the tension between asteroseismic and interferometric radii, update its fundamental parameters, and reconstruct the rotational, magnetic, and atmospheric evolution of the system. We combine forward asteroseismic modeling with seismic inversions to assess systematics from non-seismic constraints, radius measurements, and surface modeling. The revised stellar properties are then used for rotational evolution, stellar-wind, and high-energy irradiation calculations. Seismic inversions rule out the most recent interferometric radius, while the asteroseismic and spectroscopic results are compatible with the 2019 interferometric measurement. We obtain M=0.779±0.015_(stat)±0.006_(sys) M_⊙, R=0.753±0.005_(stat)±0.002_(sys) R_⊙, and an age of 8.92±0.89_(stat)±0.19_(sys) Gyr. These systematics include only non-seismic constraints; literature combined uncertainties from physical inputs and surface effects are 0.007M_⊙, 0.002R_⊙, and $0.81$ Gyr. Rotational and wind modelling shows that standard magnetic braking is broadly compatible with the present-day rotation and angular-momentum loss. Weakened braking gives a closer match but challenges standard wind-loss scalings. The inferred X-ray history suggests early stripping of the innermost planets, while the outer planets likely retained part of their primordial envelopes; HD 219134d experienced only moderate erosion. The apparent radius discrepancy likely reflects underestimated uncertainties in previous interferometric analyses rather than an astrophysical inconsistency. We advocate adopting the asteroseismic radius, which is robust to modeling assumptions and optimisation strategies.
ER -