  We propose a new method for calculating spectra and luminosities for
(anti)neutrinos produced in the pre-supernova environment by weak processes
with hot nuclei. It is based on the thermal quasiparticle random phase
approximation (TQRPA), that allows microscopic thermodynamically consistent
calculations of the weak-interaction response of nuclei at finite temperatures.
For realistic representative pre-supernova conditions from the stellar
evolution code MESA, we compute (anti)neutrino luminosities and spectra arising
from neutral- and charged-current weak reactions with hot $^{56}$Fe and compare
them with the contribution of thermal processes. We find that the TQRPA
approach produces not only a higher total luminosity of electron neutrinos
(mainly born in the electron capture reaction), compared to the standard
technique based on the large-scale shell model (LSSM) weak-interaction rates,
but also a harder neutrino spectrum. Besides, applying the TQRPA and LSSM, we
find that in the context of electron antineutrino generation, the
neutral-current nuclear de-excitation (ND) process via neutrino-antineutrino
pair emission is at least as important as the electron-positron pair
annihilation process. We also show that flavor oscillations enhance the
high-energy contribution of the ND process to the electron antineutrino flux.
This could potentially be important for pre-supernova antineutrino registration
by the Earth's detectors.
