A note on the string spectrum at the Hagedorn temperature

Abstract

We discuss semi-classical string configurations at finite temperature. We find that those soliton solution in the background describing type IIA strings disappear or become divergent when we approach the Hagedorn temperature in the strong coupling regime. These findings together with a semi-classical analysis for the Hawking radiation let us to think that Hawking radiation is mainly driven by the existence of highly excited states. As by side, we check that beside the thermodynamical instability the system is dynamical unstable before reaching the Hagedorn temperature.