A TESS Disappearing Act: The Vanishing Transits of TOI-2535 b

Planetary transits require a fortuitous alignment between a planet’s orbit and our line of sight, but dynamical interactions can render this geometric coincidence only temporary. We report the discovery of the hot Jupiter TOI-2535b, the first confirmed planet orbiting a single star whose transits have been directly observed to disappear. Over 7 yr of photometry from NASA’s Transiting Exoplanet Survey Satellite (TESS), the planet’s transit chord traversed and eventually moved off the stellar disk entirely, with an impact parameter changing at the rate of b ̇ = 0.16 yr − 1 . The transit midtimes also show significant departures of ±6 hr from a linear ephemeris. Joint modeling of the transit timing and duration variations (TTVs and TDVs) and NEID radial-velocity data indicates the presence of a nearby, mutually inclined ( i mut ≳ 5 ∘ ) planetary perturber, with the TDV being primarily due to precession of the planets’ orbital planes. Our dynamical modeling reveals that the perturber is likely of Saturn-mass or greater and in a mean-motion resonance with TOI-2535b, making this an unusual system that contains two short-period giant planets. The TDVs measured for TOI-2535b represent one of the most extreme examples of planet–planet interactions driving orbital evolution on human timescales.