Super-Eddington stellar winds driven by near-surface energy deposition

We develop analytic and numerical models of the properties of super-Eddington stellar winds, motivated by phases in stellar evolution when super-Eddington energy deposition (via, e.g., unstable fusion, wave heating, or a binary companion) heats a region near the stellar surface. This appears to occur in the giant eruptions of luminous blue variables (LBVs), Type IIn supernovae progenitors, classical novae, and X-ray bursts. We show that when the wind kinetic power exceeds Eddington, the photons are trapped and behave like a fluid. Convection does not play a significant role in the wind energy transport. The wind properties depend on the ratio of a characteristic speed in the problem v(crit) similar to(EG)(1/5) (where E is the heating rate) to the stellar escape speed near the heating region v(esc)(rh). For v(crit) greater than or similar to vesc(r(h)) the wind kinetic power at large radii E-w less than or similar to E For v(crit) less than or similar to v(esc)(r(h)), most of the energy is used to unbind the wind material and thus E-w less than or similar to E Multidimensional hydrodynamic simulations without radiation diffusion using FLASH and one-dimensional hydrodynamic simulations with radiation diffusion using MESA are in good agreement with the analytic predictions. The photon luminosity from the wind is itself super-Eddington but in many cases the photon luminosity is likely dominated by internal shocks in the wind. We discuss the application of our models to eruptive mass loss from massive stars and argue that the wind models described here can account for the broad properties of LBV outflows and the enhanced mass loss in the years prior to Type IIn core-collapse supernovae.