Absorption and emission features of <SUP>7</SUP>Be II in the outburst spectra of V838 Her (Nova Her 1991)

DOI: 
10.1093/mnras/sty2310
Publication date: 
01/08/2018
Main author: 
Selvelli, P.
IAA authors: 
Izzo, L.
Authors: 
Selvelli, P.;Molaro, P.;Izzo, L.
Journal: 
Monthly Notices of the Royal Astronomical Society
Refereed: 
Yes
Publication type: 
Article
Pages: 
2214
Abstract: 
High and low resolution 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 blue-shifted resonance doublet of singly-ionized <SUP>7</SUP>Be 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 <SUP>7</SUP>Be II λ3132 because the usual identification as the O III λ3133.7 Bowen fluorescence line is hardly compatible with both the known oxygen under-abundance in the nova ejecta and the low optical depths in the nebula due to the high outflow velocity. The average <SUP>7</SUP>Be abundance relative to hydrogen, estimated by four different methods, i.e. the <SUP>7</SUP>Be II/Mg II absorption ratio, and the <SUP>7</SUP>Be II/Mg II, <SUP>7</SUP>Be II/He II<SUB>1640</SUB>, and <SUP>7</SUP>Be II/Hβ emission ratios is N(Be)/N(H) ≈ 2.5 × 10<SUP>-5</SUP> (by number), i.e. ≈ 1.7 × 10<SUP>-4</SUP> by mass. This corresponds to an overproduction of <SUP>7</SUP>Be by about 1 dex in comparison with the theoretical models of massive CO and ONe novae. Since <SUP>7</SUP>Be all converts into <SUP>7</SUP>Li, the <SUP>7</SUP>Be/H abundance implies a <SUP>7</SUP>Li/H overabundance of about 4 dex over the <SUP>7</SUP>Li/H meteoritic value and indicates a total ejected mass of <SUP>7</SUP>Li of ≈ 9.5× 10<SUP>-10</SUP>M<SUB>☉</SUB>. These data are in line with previous observations and indicate that large amounts of <SUP>7</SUP>Li can be synthesized in a variety of novae, including very fast ONe novae.
Database: 
ADS
URL: 
https://ui.adsabs.harvard.edu/#abs/2018MNRAS.481.2261S/abstract
ADS Bibcode: 
2018MNRAS.481.2261S
Keywords: 
stars: individual V838 Her; stars: novae;nucleosynthesis;abundances; Galaxy: evolution;abundances;Astrophysics - Solar and Stellar Astrophysics