Identification and characterization of 15 265 super-Nyquist frequencies in 1309 δ Scuti stars from Kepler photometry
Abstract
The frequency of the pressure (p) mode in δ Scuti stars can exceed the Nyquist limit of Kepler long-cadence photometry. These “superNyquist frequencies” (SNFs) are observed as “reflected” peaks at lower frequencies, i.e., they are Nyquist aliases that pose a threat to asteroseismic diagnostics. Their impact on δ Scuti p modes has yet to be comprehensively explored. We performed a systematic survey to search for SNFs in 1838 Kepler δ Scuti stars through a novel technique based on a sliding Lomb-Scargle periodogram, identifying 15 265 confirmed SNFs in 1309 stars, from a total of 259 883 frequencies. We observe that the total number of detected frequencies per star remains featureless across the δ Scuti instability strip; however, young stars pulsate in higher frequencies and so have significantly more SNFs on average. Both the number and the rate of SNFs diminish accordingly as δ Scuti stars become more evolved, which is consistent with both observation and stellar models. Furthermore, our method detects a greater fraction of modes as SNFs at higher frequencies, rising from approximately 1% at 20 μHz to 23% at the Nyquist limit. The rate of underdetection is highest amongst low-amplitude modes. The SNF modulation patterns can be well distinguished from phase modulations induced by binarity or nonlinear mode interactions. We provide a frequency catalog for future asteroseismic studies of δ Scuti stars, wherein we identify each peak as being real or an alias, enabling further investigations into regular patterns of pulsation modes, linear combination frequencies, and theoretical modeling.
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BibTeX
@article{mo2026identification,
title = {{Identification and characterization of 15 265 super-Nyquist frequencies in 1309 δ Scuti stars from Kepler photometry}},
author = {Yanqi Mo and Weikai Zong and Xuan Wang and Simon Murphy and Zilu Yang and Jian-Ning Fu and Stéphane Charpinet and Xiao-Yu Ma},
journal = {Astronomy \& Astrophysics - A\&A},
year = {2026},
month = jun,
doi = {10.1051/0004-6361/202660002},
url = {https://hal.science/hal-05801742v1},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Identification and characterization of 15 265 super-Nyquist frequencies in 1309 δ Scuti stars from Kepler photometry
AU - Yanqi Mo
AU - Weikai Zong
AU - Xuan Wang
AU - Simon Murphy
AU - Zilu Yang
AU - Jian-Ning Fu
AU - Stéphane Charpinet
AU - Xiao-Yu Ma
PY - 2026
DA - 2026/06/17
JO - Astronomy & Astrophysics - A&A
DO - 10.1051/0004-6361/202660002
UR - https://hal.science/hal-05801742v1
AB - The frequency of the pressure (p) mode in δ Scuti stars can exceed the Nyquist limit of Kepler long-cadence photometry. These “superNyquist frequencies” (SNFs) are observed as “reflected” peaks at lower frequencies, i.e., they are Nyquist aliases that pose a threat to asteroseismic diagnostics. Their impact on δ Scuti p modes has yet to be comprehensively explored. We performed a systematic survey to search for SNFs in 1838 Kepler δ Scuti stars through a novel technique based on a sliding Lomb-Scargle periodogram, identifying 15 265 confirmed SNFs in 1309 stars, from a total of 259 883 frequencies. We observe that the total number of detected frequencies per star remains featureless across the δ Scuti instability strip; however, young stars pulsate in higher frequencies and so have significantly more SNFs on average. Both the number and the rate of SNFs diminish accordingly as δ Scuti stars become more evolved, which is consistent with both observation and stellar models. Furthermore, our method detects a greater fraction of modes as SNFs at higher frequencies, rising from approximately 1% at 20 μHz to 23% at the Nyquist limit. The rate of underdetection is highest amongst low-amplitude modes. The SNF modulation patterns can be well distinguished from phase modulations induced by binarity or nonlinear mode interactions. We provide a frequency catalog for future asteroseismic studies of δ Scuti stars, wherein we identify each peak as being real or an alias, enabling further investigations into regular patterns of pulsation modes, linear combination frequencies, and theoretical modeling.
SN - 0004-6361
SN - 1432-0746
ER -