  Earlier studies have suggested that deviations from the local thermodynamic
equilibrium (LTE) play a minor role in the formation of Be II 313 nm resonance
lines in solar and stellar atmospheres. Recent improvements in the atomic data
allow a more complete model atom of Be to be constructed and the validity of
these claims to be reassessed using more up-to-date atomic physics. The main
goal of this study therefore is to refocus on the role of non-local
thermodynamic equilibrium (NLTE) effects in the formation of Be II 313.04 and
313.11 nm resonance lines in solar and stellar atmospheres. For this, we
constructed a model atom of Be using new atomic data that recently became
available. The model atom contains 98 levels and 383 radiative transitions of
Be I and Be II and uses the most up-to-date collision rates with electrons and
hydrogen. This makes it the most complete model atom used to determine 1D NLTE
solar Be abundance and to study the role of NLTE effects in the formation of Be
II 313 nm resonance lines. We find that deviations from LTE have a significant
influence on the strength of the Be II 313 nm line in solar and stellar
atmospheres. For the Sun, we obtained the 1D NLTE Be abundance of A(Be)_NLTE =
1.32+/-0.05, which is in excellent agreement with the meteoritic value of
A(Be)=1.31+/-0.04. Importantly, we find that NLTE effects become significant in
FGK stars. Moreover, there is a pronounced variation in 1D NLTE-LTE abundance
corrections with the effective temperature and metallicity. Therefore, contrary
to our previous understanding, the obtained results indicate that NLTE effects
play an important role in Be line formation in stellar atmospheres and have to
be properly taken into account in Be abundance studies, especially in
metal-poor stars.
