Determining low-ℓ p-mode frequency shifts in Sun-like stars: Enhancing the cross-correlation technique with filters
Abstract
Acoustic mode frequencies in the Sun and Sun-like stars change due to magnetic activity, on time-scales much larger than the star's rotation and much smaller than its evolution. Given the poor S/N of the observed stellar p-modes, it is challenging to measure the changes of individual mode frequencies. Typically, power spectra of different time series segments are cross-correlated to estimate a mean p-mode frequency change, which ends up averaging over the individual mode contributions. We seek to enhance the cross-correlation method, by introducing a novel and computationally cheap method, thus enabling us to disentangle p-mode frequency changes for different spherical harmonic degree ℓ. Assuming that the inclination angle and rotation rate are already measured, filters are designed, which enable the isolation of δωℓ, frequency changes of modes with a given ℓ, while preventing bias creeping in from neighbouring modes. Monte-Carlo simulations are performed to quantify uncertainty in the estimation of δωℓ. We validate our method against well-studied solar data (SOHO/VIRGO and BiSON) and demonstrate its applicability to the solar-like Kepler star KIC 8006161.
Versions
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BibTeX
@misc{kashyap2026determining,
title = {{Determining low-$\ell$ p-mode frequency shifts in Sun-like stars: Enhancing the cross-correlation technique with filters}},
author = {Samarth G. Kashyap and Laurent Gizon and Jesper Schou and Rachel Howe},
howpublished = {arXiv},
year = {2026},
month = aug,
doi = {10.48550/arxiv.2608.15364},
eprint = {2608.15364},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2608.15364},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Determining low-ℓ p-mode frequency shifts in Sun-like stars: Enhancing the cross-correlation technique with filters
AU - Samarth G. Kashyap
AU - Laurent Gizon
AU - Jesper Schou
AU - Rachel Howe
PY - 2026
DA - 2026/08/30
PB - arXiv
DO - 10.48550/arxiv.2608.15364
UR - https://arxiv.org/abs/2608.15364
AB - Acoustic mode frequencies in the Sun and Sun-like stars change due to magnetic activity, on time-scales much larger than the star's rotation and much smaller than its evolution. Given the poor S/N of the observed stellar p-modes, it is challenging to measure the changes of individual mode frequencies. Typically, power spectra of different time series segments are cross-correlated to estimate a mean p-mode frequency change, which ends up averaging over the individual mode contributions. We seek to enhance the cross-correlation method, by introducing a novel and computationally cheap method, thus enabling us to disentangle p-mode frequency changes for different spherical harmonic degree ℓ. Assuming that the inclination angle and rotation rate are already measured, filters are designed, which enable the isolation of δω_ℓ, frequency changes of modes with a given ℓ, while preventing bias creeping in from neighbouring modes. Monte-Carlo simulations are performed to quantify uncertainty in the estimation of δω_ℓ. We validate our method against well-studied solar data (SOHO/VIRGO and BiSON) and demonstrate its applicability to the solar-like Kepler star KIC 8006161.
ER -