Stars can form and evolve within gaseous disks around active galactic nuclei (AGNs). In the sub-parsec region of disks around ∼108 M⊙ black holes, stars accrete rapidly, reaching ≳200 M⊙ and settling into a quasi-steady state in which accretion balances wind-driven mass loss. Within this environment, their ultimate fate depends critically on the radiative-zone diffusion coefficient (Dmix), which encapsulates various mixing processes and governs chemical transport between surface and core. Using the MESA stellar evolution code, we simulate AGN stars across a range of mixing efficiencies. We find a critical threshold floor value  that separates two distinct fates: 1. “Immortal stars”—when mixing is over-efficient (), rapid hydrogen replenishment sustains core hydrogen burning, maintains main-sequence equilibrium, rendering the star effectively “immortal.” 2. “Metamorphic stars”—when mixing is merely efficient (), stars exhaust core hydrogen, evolve off-main-sequence, shed mass to ≈15 M⊙, and produce super-solar α-abundances consistent with AGN observations. We conclude that maintaining a mixing floor below this threshold is sufficient to avoid immortality, as flux-induced extra mixing can be effectively modeled via constant floor values. Our estimates provide a foundation for future work on disk enrichment and stellar evolution.

There are currently no refbacks.