2018MNRAS.481.2261S

High- and low-resolution International Ultraviolet Explorer (IUE) spectra of V838 Her in the early outburst stages exhibit a strong absorption feature shortward of λ3130. We discuss the nature of this spectral feature and provide convincing evidence that it corresponds to the blueshifted resonance doublet of singly ionized ⁷Be recently discovered in other novae. During the evolution of the outburst the appearance of an emission feature close to λ3130 Å is also identified as ⁷Be II λ3132 because the usual identification as the O III λ3133.7 Bowen fluorescence line is hardly compatible with both the known oxygen underabundance in the nova ejecta and the low optical depths in the nebula due to the high outflow velocity. The average ⁷Be abundance relative to hydrogen, estimated by four different methods, i.e. the ⁷Be II/Mg II absorption ratio, and the ⁷Be II/Mg II, ⁷Be II/He II₁₆₄₀, and ⁷Be II/Hβ emission ratios, is N(Be)/N(H) ≃2.5 x 10^–5 (by number), i.e. ≃1.7 x 10^–4 by mass. This corresponds to an overproduction of ⁷Be by about 1 dex in comparison with the theoretical models of massive CO and ONe novae. Since ⁷Be all converts into ⁷Li, the ⁷Be/H abundance implies a ⁷Li/H overabundance of about 4 dex over the ⁷Li/H meteoritic value and indicates a total ejected mass of ⁷Li of ≃9.5 x 10^–10 M_☉. These data are in line with previous observations and indicate that large amounts of ⁷Li can be synthesized in a variety of novae, including very fast ONe novae.