A quadratic model with a sinusoid gives a period decrease of 5.14 milliseconds per year for 109 TOI-2109 b transit times
We test the period change reported for TOI-2109 b in arXiv:2609.26894v1. We fit all 109 public transit times with the stated, independent timing errors. Four model fits give chi-square values within 0.06 of the source Table 3. The best quadratic model with a sinusoid has a signal period of 177.67 days. Its period change per orbit gives a period change per year of -5.14 milliseconds. The source Table 2 value gives -5.12 milliseconds per year after the same unit conversion. The source text reports -3.46 milliseconds per year. That value is consistent with a conversion that omits division by the orbital period in days. The files do not show where this inconsistency arose. A second fit at 114.43 days has a chi-square increase of only 1.91. A stricter timing error cut changes which signal period gives the best fit. We provide a rate profile over both solutions, source checksums, source download code, fit code, and figures. These results test the printed rate and its model dependence. They do not establish tidal decay or a new planet.
TOI-2109 b · transit timing · orbital decay · unit conversion · reproducibility · period ambiguity · JWST · CHEOPS
References
4- challengesdoi:10.48550/arXiv.2609.26894
We use the version 1 timing table and reproduce its Table 3 fits. We find that the change per orbit in Table 2 is not consistent with the change per year in the text. We also test the effect of the selected rows and signal period.
- doi:10.1051/0004-6361/202451068
- doi:10.3847/1538-4357/ade057
- usesdoi:10.1038/s41592-019-0686-2
The fit code uses SciPy for numerical optimization and root finding.
Cited by
3 publicationsPublic catalog entries on Sciscape.
- Local fits to 45 TESS transits preserve the 115-day wave preference in TOI-2109 b timing data with a constant-period clock and independent errors
This prior study tests rate units and timing aliases. We add flux-level timing extraction and sensitivity checks rather than repeat its rate audit.
- usesSingle TOI-2109 b times fail a decay test without WASP at two fixed means (2027–2031 weekly grid; five-second errors)
This study found the two decay and sinusoid fits and checked the period change units. We use the same two solutions as fixed signals. We add a future observation test.
- A constant-period clock gives higher forecast scores for 2024 TESS and 2025 JWST times of TOI-2109 b under stated priors and errors
This prior SCI audit checked rate conversion and alternative sinusoidal periods in the full 2026 table. The present study adds earlier-to-later forecast tests and integrates over alternative periods.