Absorption and emission features of 7Be ii in the outburst spectra of V838 Her (Nova Her 1991)

Selvelli, P. L.; Molaro, P.; Izzo, L.

doi:10.1093/mnras/sty2310

Cited by 28 publications

(35 citation statements)

References 77 publications

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“…As 7 Be was detected in more objects (e.g. Selvelli et al 2018;Molaro et al 2020b), a discrepancy between the observational abundance estimates and theoretical predictions of nucleosynthesis models became apparent, with the former exceeding the latter by up to one order of magnitude. The reason for this may reside in the (wrong) assumption of equality between the relative fractions of the ions Be ii/Be and Ca ii/Ca in the nova ejecta (Chugai & Kudryashov 2020) and/or in an overly simplistic treatment of the complex structure of the ejecta itself (Shore & De Gennaro Aquino 2020).…”

Section: Introductionmentioning

confidence: 99%

The Gaia-ESO Survey: Galactic evolution of lithium from iDR6

Romano¹,

Magrini

Randich

et al. 2021

A&A

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Context. After more than 50 years, astronomical research still struggles to reconstruct the history of lithium enrichment in the Galaxy and to establish the relative importance of the various 7Li sources in enriching the interstellar medium (ISM) with this fragile element. Aims. To better trace the evolution of lithium in the Milky Way discs, we exploit the unique characteristics of a sample of open clusters (OCs) and field stars for which high-precision 7Li abundances and stellar parameters are homogeneously derived by the Gaia-ESO Survey (GES). Methods. We derive possibly un-depleted 7Li abundances for 26 OCs and star forming regions with ages from young (∼3 Myr) to old (∼4.5 Gyr), spanning a large range of galactocentric distances, 5 < RGC/kpc < 15, which allows us to reconstruct the local late Galactic evolution of lithium as well as its current abundance gradient along the disc. Field stars are added to look further back in time and to constrain 7Li evolution in other Galactic components. The data are then compared to theoretical tracks from chemical evolution models that implement different 7Li forges. Results. Thanks to the homogeneity of the GES analysis, we can combine the maximum average 7Li abundances derived for the clusters with 7Li measurements in field stars. We find that the upper envelope of the 7Li abundances measured in field stars of nearly solar metallicities (−0.3 < [Fe/H]/dex < +0.3) traces very well the level of lithium enrichment attained by the ISM as inferred from observations of cluster stars in the same metallicity range. We confirm previous findings that the abundance of 7Li in the solar neighbourhood does not decrease at super-solar metallicity. The comparison of the data with the chemical evolution model predictions favours a scenario in which the majority of the 7Li abundance in meteorites comes from novae. Current data also seem to suggest that the nova rate flattens out at later times. This requirement might have implications for the masses of the white dwarf nova progenitors and deserves further investigation. Neutrino-induced reactions taking place in core-collapse supernovae also produce some fresh lithium. This likely makes a negligible contribution to the meteoritic abundance, but could be responsible for a mild increase in the 7Li abundance in the ISM of low-metallicity systems that would counterbalance the astration processes.

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Section: Introductionmentioning

confidence: 99%

The Gaia-ESO Survey: Galactic evolution of lithium from iDR6

Romano¹,

Magrini

Randich

et al. 2021

A&A

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“…Such structures have been identified in classical novae from long time series in the optical and UV (e.g., De Gennaro Aquino et al 2014, Shore et al 2016, Mason et al 2018, appearing as persistent features in radial velocity whose optical depths scale with the expansion 2 . These structures were shifted in radial velocity by amounts similar to those in Tajitsu et al (2015), Izzo et al (2015), or Selvelli et al (2018), on the order of 1000-1200 km s −1 . Since we are solving the radiative transfer problem within an imposed dynamical framework, we can perform this shift.…”

Section: Parameter Units Range Stepmentioning

confidence: 83%

“…However, a comparison (Fig. 2) with the IUE spectrum of the extreme ONe nova V838 Her (Selvelli et al 2018) shows that the feature at 3131 Å cannot be unambiguously interpreted as Be ii. The models for a Be overabundance of 4 dex show an extremely strong absorption, only a fraction of which is contributed by the Be ii doublet, and more significantly it also shows an emission feature that is not observed in the V838 Her comparisons.…”

Section: Be II 3131 åmentioning

confidence: 99%

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NLTE modeling and spectroscopically derived abundances of lithium and beryllium for classical nova ejecta

Shore

Aquino

2020

A&A

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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 Li I and Be II 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 Be II 3130 Å than those so far observed. A similar overabundance for Li would instead result in a barely observable change in the emitted flux at Li I 6709 Å. The observed extended absorption feature at 3131 Å 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.

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“…Triângulos mostram limites superiores em A (Li). foram relatadas na literatura recentemente (Izzo et al, 2015;Tajitsu et al, 2015Tajitsu et al, , 2016Molaro et al, 2016;Izzo et al, 2018;Selvelli et al, 2018), enquanto o trabalho de Starrfield et al (2020) nos abastece com simulações que indicam grande produção e ejeção de 7 Be por novas, sugerindo que são uma contribuição importante para o enriquecimento em Li do disco fino.…”

Section: Capítulounclassified

Abundâncias químicas de estrelas anãs G e K e modelos de evolução estelar para [Fe/H]=-1.8 e [Fe/H]=-1.0 com enriquecimento-alpha

Carlos¹

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O estudo de composição química das estrelasé crucial para o entendimento tanto sobre estrutura estelar quanto sobre a história de formação da nossa galáxia.Levando em consideração que o elemento Lié um dos mais importantes traçadores astrofísicos sobre mecanismos de transporte e mistura dentro e abaixo da zona convectiva de estrelas do tipo tardio, concluímos um estudo abrangente sobre depleção de Li em 85 gêmeas solares do campo na vizinhança solar, e mais três gêmeas solares do aglomerado aberto M67. Encontramos uma forte correlação entre depleção de Li e idade estelar, em acordo com modelos não-padrão de evolução estelar. Observamos, também, que o Sol pode ser considerado pobre em Li em comparação a outras gêmeas solares de idades similares (por um fator de ∼ 2σ). Nossos resultados também sugerem que estrelas com os mais baixos conteúdos de Li, para uma dada idade, são acompanhadas de baixos níveis de elementos refratários. Analisamos 8 estrelas anãs K do halo da Galáxia para mais informações sobre a formação dessa componente galáctica, concluindo uma análise química detalhada dos elementos C,

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Absorption and emission features of 7Be ii in the outburst spectra of V838 Her (Nova Her 1991)

Cited by 28 publications

References 77 publications

The Gaia-ESO Survey: Galactic evolution of lithium from iDR6

The Gaia-ESO Survey: Galactic evolution of lithium from iDR6

NLTE modeling and spectroscopically derived abundances of lithium and beryllium for classical nova ejecta

Abundâncias químicas de estrelas anãs G e K e modelos de evolução estelar para [Fe/H]=-1.8 e [Fe/H]=-1.0 com enriquecimento-alpha

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