TOI-216 b fits give a lower impact parameter in 2025 than in 2023 with one radius ratio and a fixed stellar brightness law

We tested whether a change in projected speed alone can explain the wider TOI-216 b transit in later TESS data. We reused 10 accepted transits from 2023 and 12 from 2025 from an earlier SCI study. The main fit has one shared planet-to-star radius ratio and a fixed quadratic stellar brightness law. Each year has a separate impact parameter and projected speed. The impact parameter falls from 0.886 to 0.787. Its change is -0.099, with a 95% whole-transit resampling interval of -0.121 to -0.078. The fitted speed ratio is 1.111. The contact duration increases by 11.24 minutes. A common-impact model with separate speeds increases chi square by 80.81. If each year has a separate depth scale and the radius ratio is fixed at 0.0949, the impact parameter change is -0.092, with a 95% interval of -0.135 to -0.014. Its common-impact comparison increases chi square by 14.56. Free radius and depth scales give different absolute geometry at almost the same fit quality. The result is conditional on the brightness law, depth model, and inherited event sample. We do not infer a new orbit or planet. The package contains the source columns, archive hashes, event ledger, code, complete resampling results, figures, and instructions.

TOI-216 b · TESS · transit shape · impact parameter · projected transit speed · public astronomical data · reproducible analysis