2020A&A...639L..12S

Context. Extreme super-solar abundances of lithium and beryllium have been reported in recent years for classical novae based on absorption lines in ultraviolet and optical spectra during the optically thick stages, but these findings have not been compared with spectrum syntheses of the ejecta.
Aims. We present a grid of nova ejecta models calculated with PHOENIX aimed at simulating the reported LiI and BeII features with super-solar abundances.
Methods. We computed a sequence of models, finely exploring the parameter space of effective temperature, ejecta expansion velocity, and Li and Be overabundances.
Results. Regardless of temperature and expansion velocity, the synthetic spectra for large Li and Be overabundances strongly disagree with those presented in recent literature. Assuming a wide range of Be overabundances (factors of 100 to 10 000 relative to solar), we predict a much stronger spectroscopic feature at BeII 3130Å than those so far observed. A similar overabundance for Li would instead result in a barely observable change in the emitted flux at LiI 6709Å. The observed extended absorption feature at 3131Å reported in V838 Her and other novae appears even in zero-Be models with only solar abundances (which for novae are underestimates).
Conclusions. The computed spectra do not support the lithium and beryllium abundances, and caution is warranted in the interpretation of the phenomenology.