  Star clusters in isothermal spheres are studied from a thermodynamic point of
view. New density profiles are presented, that describe the collapsed phase at
low temperatures. At the transition a set of binaries is formed that carries 13
% of the gravitational energy, while also a huge latent heat is generated. The
total energy of the binaries is fixed by thermodynamics. In the canonical
ensemble all specific heats are positive, while previously discussed negative
specific heat solutions are metastable. In a microcanonical ensemble the latter
remain partly dominant.
