K Dwarf Radius Inflation and a 10 Gyr Spin-down Clock Unveiled through Asteroseismology of HD 219134 from the Keck Planet Finder

Abstract We present the first asteroseismic analysis of the K3 V planet host HD 219134 based on four consecutive nights of radial velocities collected with the Keck Planet Finder. We apply Gold deconvolution to the power spectrum to disentangle modes from side lobes in the spectral window and extract 25 mode frequencies with spherical degrees 0 ≤ ℓ ≤ 3. We derive the fundamental properties using five different evolutionary-modeling pipelines and report a mass of 0.763 ± 0.020 (stat) ± 0.007 (sys) M ⊙ , a radius of 0.748 ± 0.007 (stat) ± 0.002 (sys) R ⊙ , and an age of 10.151 ± 1.520 (stat) ± 0.810 (sys) Gyr. Compared to the interferometric radius 0.783 ± 0.005 R ⊙ , the asteroseismic radius is 4% smaller at the 4 σ level—a discrepancy not easily explained by known interferometric systematics, modeling assumptions on atmospheric boundary conditions and mixing lengths, magnetic fields, or tidal heating. HD 219134 is the first main-sequence star cooler than 5000 K with an asteroseismic age estimate and will serve as a critical calibration point for stellar spin-down relations. We show that existing calibrated prescriptions for angular momentum loss, incorporating weakened magnetic braking with asteroseismically constrained stellar parameters, accurately reproduce the observed rotation period. Additionally, we revised the masses and radii of the super-Earths in the system, which support their having Earth-like compositions. Finally, we confirm that the oscillation amplitude in radial velocity scales as ( L / M ) 1.5 in K dwarfs, in contrast to the ( L / M ) 0.7 relation observed in G dwarfs. These findings provide significant insights into the structure and angular momentum loss of K-type stars.

Authors

Publication Details

Journal
The Astrophysical Journal
Published
2025-05-06
DOI
https://doi.org/10.3847/1538-4357/adc737
Citations
11
Primary Topic
Stellar, planetary, and galactic studies
Type
article
Field-Weighted Citation Impact
12.70

Funders

Controls
|||
ALL TIME
JAN
FEB
MAR
APR
MAY
JUN
JUL
AUG
SEP
OCT
article

K Dwarf Radius Inflation and a 10 Gyr Spin-down Clock Unveiled through Asteroseismology of HD 219134 from the Keck Planet Finder

Samuel Halverson, Howard Isaacson, J. M. Joel Ong, Chris Smith et al.
11 citations
The Astrophysical Journal
Stellar, planetary, and galactic studies
12.70
article

K Dwarf Radius Inflation and a 10 Gyr Spin-down Clock Unveiled through Asteroseismology of HD 219134 from the Keck Planet Finder

Samuel Halverson, Howard Isaacson, J. M. Joel Ong, Chris Smith, Fei 飞 Dai 戴, Andrew W. Howard, Theron W. Carmichael, T. L. Campante, M. Lundkvist, Daniel Huber, Arpita Roy, Benjamin J. Fulton, Daniel Hey, H. Kjeldsen, Raquel Costa, Ashley Baker, Ashley Chontos, Steven R. Gibson, T. R. Bedding, Jennifer L. van Saders, M. J. P. F. G. Monteiro, Marc Hon, Kodi Rider, Sarbani Basu, Josh Walawender, Nicholas Saunders, Yaguang Li, J. R. Larsen, Jerry Edelstein
article en
11 citations

Abstract

Abstract We present the first asteroseismic analysis of the K3 V planet host HD 219134 based on four consecutive nights of radial velocities collected with the Keck Planet Finder. We apply Gold deconvolution to the power spectrum to disentangle modes from side lobes in the spectral window and extract 25 mode frequencies with spherical degrees 0 ≤ ℓ ≤ 3. We derive the fundamental properties using five different evolutionary-modeling pipelines and report a mass of 0.763 ± 0.020 (stat) ± 0.007 (sys) M ⊙ , a radius of 0.748 ± 0.007 (stat) ± 0.002 (sys) R ⊙ , and an age of 10.151 ± 1.520 (stat) ± 0.810 (sys) Gyr. Compared to the interferometric radius 0.783 ± 0.005 R ⊙ , the asteroseismic radius is 4% smaller at the 4 σ level—a discrepancy not easily explained by known interferometric systematics, modeling assumptions on atmospheric boundary conditions and mixing lengths, magnetic fields, or tidal heating. HD 219134 is the first main-sequence star cooler than 5000 K with an asteroseismic age estimate and will serve as a critical calibration point for stellar spin-down relations. We show that existing calibrated prescriptions for angular momentum loss, incorporating weakened magnetic braking with asteroseismically constrained stellar parameters, accurately reproduce the observed rotation period. Additionally, we revised the masses and radii of the super-Earths in the system, which support their having Earth-like compositions. Finally, we confirm that the oscillation amplitude in radial velocity scales as ( L / M ) 1.5 in K dwarfs, in contrast to the ( L / M ) 0.7 relation observed in G dwarfs. These findings provide significant insights into the structure and angular momentum loss of K-type stars.

The Astrophysical JournalVol. 984(2)
National Aeronautics and Space Administration, Villum Fonden
Openalex Percentile: Top 1%
Stellar, planetary, and galactic studies
12.70
DOIOpen Access PDFOpenAlex
AI Navigator

Ask Laika to Summarize, Analyze, and Connect papers live on the map.

Summarize Papers & Methodologies

Extract key findings, datasets, and comparative methods across publications.

Benchmark Rankings & Visual Analytics

Rank top research institutions, authors, funders, topics, and journals by Field-Weighted Citation Impact (FWCI) and paper volume with instant charts.

Connect Distant Disciplines

Bridge topological clusters on the map to find hidden collaborative intersections.