The Photogravitational Parameter Φ: A Surface-First Diagnostic for Luminous Stars

This paper extends stellar evolution theory to include general relativistic effects near the Eddington limit. We show that gravitational redshift reduces the effective Eddington luminosity by √(1 − 2GM/Rc²), modifying the exponential expansion law for unstable envelopes. The framework introduces the photogravitational parameter Φ = L/(Mg), constructed from observable quantities: luminosity, mass, and surface gravity. This enables consistency tests without opacity uncertainties that plague traditional models. Applications to Wolf Rayet stars and Luminous Blue Variables reveal that relativistic corrections exceed 1% when compactness β > 0.01. The approach bridges stellar surface physics with horizon thermodynamics, providing testable predictions for extreme stellar systems. Key result:Stellar envelopes expand slower in curved spacetime, with the timescale lengthening by (1 − 2GM/Rc²)^−1/2 relative to classical predictions.