SUPERWIND MODELS FOR THE DUST SHELLS AROUND OH IR STARS/

We have modeled the dust envelopes around OH/IR stars with the changes in the dust density distribution that are expected from a superwind p hase. We explore the effect of a superwind due to a helium shell flash by adding a density-enhanced region that proceeds outward. Depending on the position and the degree of the enhancement, the emergent model spectral energy distributions can be significantly different from the ones with the conventional power-law density distributions. The time e volution of the spectral energy distribution of a superwind can, at ce rtain times, explain some observations of OH/IR stars. However, at oth er times in the evolution of a superwind, spectral energy distribution s and optical depths that are not observed often result.