It has long been speculated that a black hole in string theory turns into highly excited strings close to the Hagedorn temperature. Gravitational attraction pulls different parts of the string together, forming a star-like configuration. In this talk, I will review the properties of a concrete solution of this kind, first discovered by Horowitz and Polchinski. I will discuss whether the Horowitz-Polchinski solution can be smoothly connected with the black hole as worldsheet CFTs.

If time permit, I will discuss an ongoing work on the spectral form factor of a gas of strings, which probes the finer details of the spectrum. I will highlight the importance of a potential family of generalizations of the Horowitz-Polchinski solution.