Highly Enriched 7Be in the ejecta of Nova Sagittarii 2015 No. 2 (V5668
  Sgr) and the Galactic Lithium origin
  We report on the evidence of highly blue-shifted resonance lines of the
singly ionised isotope of 7BeII in high resolution UVES spectra of Nova
Sagittarii 2015 No. 2 (V5668 Sgr). The resonance doublet lines 7BeII at lambda
313.0583, 313.1228 nm are clearly detected in several non saturated and
partially resolved high velocity components during the evolution of the
outburst. The total absorption identified with Beryllium has an equivalent
width much larger than all other elements and comparable to hydrogen. We
estimate an atomic fraction N(7Be)/N(Ca) ~ 53-69 from unsaturated and resolved
absorption components. The detection of 7Be in several high velocity components
shows that it has been freshly created in a thermonuclear runaway via the
reaction 3He}(alpha,gamma) 7Be during the Nova explosion, as postulated by
Arnould and Norgaard (1975) , however in much larger amounts than predicted by
current models. 7Be decays to 7Li with a half-life of 53.22 days, comparable to
the temporal span covered by the observations. The non detection of LiI
requires that LiII remains ionised throughout our observations. The massive 7Be
ejecta result into a 7Li production that is about 4.7-4.9 dex above the
meteoritic abundance. If such a high production is common even in a small
fraction (~5%) of Novae, they can make all the "stellar" 7Li of the Milky Way.
