Extremal Hawking radiation

The particle spectrum for collapse to an extremal Reissner-Nordström black hole is solved by use of the corresponding moving mirror model. The amount of particles and energy flux is symmetric in delayed null time as received by an observer at infinity. The star emits a total finite amount of energy carried by particles that are not specified by a temperature. The finite energy limits the evaporation process yet an infinite amount of particles with zero frequency characterize the radiation. At ultralate times the particle emission spectrum is that of a uniformly accelerated mirror.