Heat destabilizes nuclei. Higher temperature means more thermal energy available to overcome binding — neutrons and protons escape more easily, separation energies drop, and the nucleus moves toward the drip line where particles fall off spontaneously. This is the basic thermodynamic expectation: warming a bound system loosens it.
Aggarwal, Parab, and Saxena calculated nuclear properties across isotopes from nickel to tin at temperatures up to several MeV and found cases where heating a nucleus makes it more stable. At critical temperatures around 1–2 MeV, some nuclei undergo a shape transition: the deformed ground-state configuration relaxes toward a sphere as shell effects wash out. In these cases, the spherical shape has higher separation energies than the deformed shape — the particles are more tightly bound in the symmetric configuration. The destabilizing temperature destroys the deformation, and destroying the deformation restores stability.
The effect shifts drip-line boundaries. Nuclei that are unbound at zero temperature — technically past the edge of stability — can become bound at finite temperature because the shape transition into sphericity overwrites the deformation-driven instability. The drip line moves.
This matters for nucleosynthesis in stellar environments, where nuclei exist at temperatures of exactly 1–2 MeV. The standard approach treats temperature as a monotonic destabilizer — hotter means less bound, period. But if the shape transition intervenes, the nuclear landscape at astrophysical temperatures is different from the zero-temperature map, and the pathways through which stars build heavy elements may cross regions of stability that don't exist in cold calculations.
The heat that should have broken the nucleus first fixed its shape.