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Peer-reviewedCC BY 4.0The Astrophysical Journal

Study of Special Pulsation Modulation Phenomena: A Case Study of the δ Scuti Star KIC 4737720

  • Jianwei Yao1,2
  • Ali Esamdin1,2
  • Haozhi Wang3
  • Chenglong Lv1,4
  • Shuguo Ma1
  • Ayzada Jumahali1,2
  • Kedieryemu Kamili5
5 affiliations
  1. 1Chinese Academy of Sciences
  2. 2University of Chinese Academy of Sciences
  3. 3Chinese Academy of Sciences South America Center for Astronomy
  4. 4Instituto de Astrofísica de Andalucía - CSIC
  5. 5School of Physical Science and Technology Xinjiang University
Open at sourcePDFDOICite

Abstract

Using corrected long-baseline Kepler and TESS photometry, we investigated the pulsation modulation of the δ Scuti star KIC 4737720. The observed frequency ratio F ₀ / F ₁ ≃ 0.77 is compatible with interpreting F ₀ and F ₁ as candidate radial fundamental and first-overtone modes, although the rapid rotation of the star prevents a secure mode identification. Hilbert-envelope analysis reveals a quasi-triplet centered on F T that satisfies F ₀ ≃ F T − f m1 + f m2 . Because the component at the F ₀ sidelobe position becomes dominant during part of the Kepler observations, this structure is difficult to explain solely by simple weak modulation and may also involve nonlinear modulation, combination frequencies, or mode coupling. Fixed-frequency time-dependent analysis of the Kepler data shows that the dominant component changes from F ₀ = 19.204794 day ⁻¹ to F ₁ = 24.89813 day ⁻¹ , whereas both the 600 s and 200 s TESS data independently identify F T = 20.37206 day ⁻¹ as the highest-amplitude component at the later epoch. The principal frequency positions remain nearly stable, indicating that the observed variability is dominated by changes in the relative amplitudes of the frequency components rather than by secular frequency drift. The agreement between f rot sin i = 1.19 ± 0.06 day − 1 and f m1 ≃ 1.23 day ⁻¹ suggests that stellar rotation may set the characteristic timescale of the modulation. Target-pixel-file diagnostics further show that the V-shaped frequency drifts in the range 15–18 day ⁻¹ recur on a timescale close to the Kepler annual roll period, indicating that they are most likely instrumental in origin.

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Cite

BibTeXRIS
BibTeX
@article{yao2026study,
  title = {{Study of Special Pulsation Modulation Phenomena: A Case Study of the δ Scuti Star KIC 4737720}},
  author = {Jianwei Yao and Ali Esamdin and Haozhi Wang and Chenglong Lv and Shuguo Ma and Ayzada Jumahali and Kedieryemu Kamili},
  journal = {The Astrophysical Journal},
  year = {2026},
  month = oct,
  doi = {10.3847/1538-4357/aea20a},
  url = {https://iopscience.iop.org/article/10.3847/1538-4357/aea20a},
  note = {CC BY 4.0},
}
RIS
TY  - JOUR
TI  - Study of Special Pulsation Modulation Phenomena: A Case Study of the δ Scuti Star KIC 4737720
AU  - Jianwei Yao
AU  - Ali Esamdin
AU  - Haozhi Wang
AU  - Chenglong Lv
AU  - Shuguo Ma
AU  - Ayzada Jumahali
AU  - Kedieryemu Kamili
PY  - 2026
DA  - 2026/10/15
JO  - The Astrophysical Journal
DO  - 10.3847/1538-4357/aea20a
UR  - https://iopscience.iop.org/article/10.3847/1538-4357/aea20a
AB  - Using corrected long-baseline Kepler and TESS photometry, we investigated the pulsation modulation of the δ Scuti star KIC 4737720. The observed frequency ratio F ₀ / F ₁ ≃ 0.77 is compatible with interpreting F ₀ and F ₁ as candidate radial fundamental and first-overtone modes, although the rapid rotation of the star prevents a secure mode identification. Hilbert-envelope analysis reveals a quasi-triplet centered on F T that satisfies F ₀ ≃ F T − f m1 + f m2 . Because the component at the F ₀ sidelobe position becomes dominant during part of the Kepler observations, this structure is difficult to explain solely by simple weak modulation and may also involve nonlinear modulation, combination frequencies, or mode coupling. Fixed-frequency time-dependent analysis of the Kepler data shows that the dominant component changes from F ₀ = 19.204794 day ⁻¹ to F ₁ = 24.89813 day ⁻¹ , whereas both the 600 s and 200 s TESS data independently identify F T = 20.37206 day ⁻¹ as the highest-amplitude component at the later epoch. The principal frequency positions remain nearly stable, indicating that the observed variability is dominated by changes in the relative amplitudes of the frequency components rather than by secular frequency drift. The agreement between f rot sin i = 1.19 ± 0.06 day − 1 and f m1 ≃ 1.23 day ⁻¹ suggests that stellar rotation may set the characteristic timescale of the modulation. Target-pixel-file diagnostics further show that the V-shaped frequency drifts in the range 15–18 day ⁻¹ recur on a timescale close to the Kepler annual roll period, indicating that they are most likely instrumental in origin.
SN  - 0004-637X
SN  - 1538-4357
ER  -