Stellar Evolution with Radiative Feedback in AGN Disks

Abstract Stars embedded in the inner parsec region of an active galactic nucleus (AGN) experience extreme accretion conditions that significantly alter their evolution. We present one-dimensional MESA simulations of stars growing and decaying within AGN disks, implementing radiative-feedback-regulated accretion, limiting stellar growth near the Eddington luminosity, as well as wind-driven mass loss. Unlike stand-alone stars in the field, these embedded stars follow unique evolutionary tracks with well-determined mass evolution and chemical yields. We distinguish two regimes: “immortal” stars that indefinitely remain on the main sequence due to efficient hydrogen mixing; and “metamorphic” stars whose growth is limited by feedback, ultimately enriching the disk with heavy elements upon hydrogen and helium exhaustion in their cores. Results indicate that embedded stars in AGN disks can attain large masses, but radiative feedback, gas retention, and limited mixing likely ensure the “immortal” track is unsustainable. Embedded metamorphic stars significantly enrich AGN disks with helium and α -elements, potentially explaining the observed high metallicity in broad-line regions (BLR) without excessive helium enrichment. This study underscores the critical interplay between stellar feedback and accretion physics in shaping the stellar populations and chemical evolution within AGN disks.