  The frozen star model provides a classical description of a regularized black
hole and is based upon the idea that regularizing the singularity requires
deviations from the Schwarzschild geometry which extend over horizon-sized
scales, as well as maximally negative radial pressure as an equation of state.
The frozen star has also been shown to be ultra-stable against perturbations; a
feature that can be attributed to the equation of state and corresponds to this
model mimicking a black hole in the limit $\hbar\to 0$ or, equivalently, the
limit of infinite Newton's constant. Here, we ``defrost'' the frozen star by
allowing its radial pressure to be perturbatively less negative than maximal.
This modification to the equation of state is implemented by appropriately
deforming the background metric so as to allow the frozen star to mimic a
quantum black hole at finite $\hbar$ and Newton's constant. As a consequence,
the defrosted star acquires a non-trivial spectrum of oscillatory
perturbations. To show this, we first use the Cowling approximation to obtain
generic equations for the energy density and pressure perturbations of a
static, spherically symmetric background with an anisotropic fluid. The
particular setting of a deformed frozen star is then considered, for which the
dispersion relation is obtained to leading order in terms of the deviation from
maximal pressure. The current results compare favorably with those obtained
earlier for the collapsed polymer model, whose strongly non-classical interior
is argued to provide a microscopic description of the frozen and defrosted star
geometries.
