Fate and lifetime of quasi-stars when the inner boundary exceeds the stellar radius

Determine the physical evolution and total lifetime of quasi-stars modeled in MESA-QUEST when the saturated-convection inner boundary condition (used as the inner radius around the central black hole) grows to exceed the total stellar radius, including whether accretion onto the central black hole continues and how this affects the remaining lifetime of the quasi-star.

Background

In the MESA-QUEST framework, quasi-stars are modeled by imposing inner boundary conditions at the saturated-convection radius to represent an accreting black hole embedded within a massive envelope. The accretion luminosity is tied to the Eddington limit of the full object, and the models trace evolutionary tracks including a long late-stage on the Hayashi track.

While individual tracks yield a nominal lifetime of about 20 Myr for a 10^6 solar-mass quasi-star, the authors note uncertainty in the terminal phase when the prescribed inner boundary may expand beyond the stellar surface. Clarifying the behavior of the envelope and accretion in this regime is necessary to establish the actual lifetime and end-state of quasi-stars within these models.