Formation-to-Present Reconstruction of WASP-12b: Stable Survival of a Persistently Roche-Distorted Hot Jupiter

WASP-12b is among the most extreme exoplanets currently known, exhibiting intense stellar irradiation, ongoing atmospheric escape, anomalous radius inflation, and a demonstrably non-spherical, Roche-distorted geometry. While its present-day orbital and physical properties are well constrained observationally, the evolutionary pathway that produced and sustains this configuration has remained unresolved. In particular, it has been unclear whether such a planet represents a transient, terminal phase of destruction or a dynamically stable outcome of planetary evolution under extreme conditions. This study presents the first continuous, forward-time reconstruction of WASP-12b’s evolution from formation within a protoplanetary disk to its present observed state. Rather than assuming the current configuration as an initial condition, the system is evolved forward in time under physically constrained processes including disk-driven migration, post-disk eccentricity excitation, tidal circularization, sustained tidal heating, Roche-lobe interaction, atmospheric mass loss, and orbital angular momentum exchange. Large ensembles of realizations are generated to explore uncertainty space and identify physically admissible evolutionary trajectories. The results demonstrate that WASP-12b’s present lemon-shaped geometry is not a fleeting anomaly but the endpoint of a narrow yet robust evolutionary corridor. Early inward migration followed by high-eccentricity excitation enables prolonged tidal dissipation, maintaining an inflated radius and stabilizing Roche distortion without triggering runaway disruption. Angular momentum exchange and regulated mass loss act to halt rapid inspiral, producing a long-lived configuration consistent with all major observational constraints. Crucially, the reconstruction shows that persistent non-spherical planetary geometries can remain dynamically and structurally stable over gigayear timescales. Roche distortion alone does not imply imminent destruction, and extreme hot Jupiters may represent survivable evolutionary endpoints rather than transient phases. The rarity of systems like WASP-12b arises naturally from the narrowness of the survivable parameter space, not from inherent instability. This work reframes the interpretation of extreme exoplanets and provides a generalizable framework for distinguishing transient phenomena from stable evolutionary outcomes in ultra-short-period planetary systems.