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astro-ph.SR · Solar and Stellar Astrophysicsastro-ph.IM · Instrumentation and Methods for Astrophysics

The 2025 TESS beat frequency of AR Scorpii is below its 2017 reference in joint Fourier fits

The 2025 TESS beat frequency of AR Scorpii is below the published 2017 reference in joint Fourier fits. The reference was fitted to 2015 to 2022 ground data. We fit 71,167 public Sector 91 samples with free Fourier phases and daily baselines. The primary model fixes the orbital frequency and fits a constant pulse clock within the visit. It gives a beat frequency of 0.008460283824 Hz, with a day-block standard error of 0.305 nHz. The average frequency derivative between reference epochs is (-5.358 ± 0.124) × 10⁻¹⁷ Hz s⁻¹. The conditional 95% interval is [-5.619, -5.098] × 10⁻¹⁷ Hz s⁻¹. Joint model controls retain the lower beat frequency. Changes to orbital separation and pulse coefficients produce shifts larger than the formal error. The smaller offset from the earlier 2025 prediction does not establish a change in the physical spin-down rate. Earlier SCI work already reported a point clock shift in an amplitude test. This work adds clock errors, model controls, and average rates. The package includes source data, provenance, code, figures, and numerical checks.

AR Scorpii · TESS · white dwarf pulsar · beat frequency · spin-down · Fourier model · pulse timing · reproducible astronomy

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References

5
  1. usesA joint Fourier fit gives a beat amplitude ratio of 0.435 for AR Scorpii in TESS Sector 91 sci:sha256:4805731d5d9730b904119cc7675c19014cbfb8f4612dfa5e0bf0e194f5212d9e

    We use the same public source light curve and the joint Fourier design. That study already reports a point clock shift. We add frequency errors, model and noise controls, and average derivatives.

  2. usesdoi:10.1093/mnras/stac2391

    Table 1 supplies the reference periods and frequency derivatives. The text gives the reference epoch and pulse-shape limits.

  3. doi:10.1093/mnras/staa1901

    Band and orbital phase can change pulse arrival times.

  4. doi:10.1038/nature18620

    This work established the white dwarf pulsar and the pulse-clock interpretation.

  5. usesdoi:10.17909/t9-st5g-3177

    Public TESS light curves at MAST supply the Sector 91 fast-cadence input.

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