A coplanar, edge-on two-planet model fits four TOI-2180 transit times and 152 velocities at a fixed stellar mass of 1.17 solar masses

The known outer radial velocity companion of TOI-2180 can account for four transit times in a Newtonian model. We fit all 152 published radial velocities and four times from TESS sectors 19, 48, 57, and 86. The primary model assumes a stellar mass of 1.17 solar masses and two coplanar orbits seen edge on. Its velocity residual root mean square is 5.49 m/s. The timing residuals are +0.63, -2.38, +2.04, and -3.50 minutes. Each is inside its source error or practical allowance. The fourth time comes from a prior SCI study of data with stray light flags. Its 0.020-day practical allowance is not a probability interval. A fit that omits this time predicts it 6.65 hours early with almost the same velocity scatter. Distinct outer periods also fit, so the data do not select one unique orbit. A separate gravity solver and apparent-position calculation agree with the transit times to 0.0036 second. The primary example completes a 100000-year numerical survival test. The publication preserves the source table, provenance, code, orbit vectors, initial states, per-measurement predictions, figures, and reproduction instructions. This is a conditional feasibility result. It does not establish a new planet or prove the cause of the timing changes.

TOI-2180 · transit timing · radial velocity · Newtonian dynamics · TESS · REBOUND · reproducible research