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Journal Articles Monthly Notices of the Royal Astronomical Society Year : 2022

Detection of 7Be II in the Small Magellanic Cloud

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Luca Izzo
  • Function : Author
Paolo Molaro
  • Function : Author
Gabriele Cescutti
  • Function : Author
Elias Aydi
  • Function : Author
Pierluigi Selvelli
  • Function : Author
Eamonn Harvey
  • Function : Author
Adriano Agnello
  • Function : Author
Massimo Della Valle
  • Function : Author
Ernesto Guido
  • Function : Author
Margarita Hernanz
  • Function : Author

Abstract

We analyse high-resolution spectra of two classical novae that exploded in the Small Magellanic Cloud (SMC). 7Be II resonance transitions are detected in both ASASSN-19qv and ASASSN-20ni novae. This is the first detection outside the Galaxy and confirms that thermo-nuclear runaway reactions, leading to the 7Be formation, are effective also in the low-metallicity regime, characteristic of the SMC. Derived yields are of N(7Be = 7Li)/N(H) = (5.3 ± 0.2) × 10-6 which are a factor 4 lower than the typical values of the Galaxy. Inspection of two historical novae in the Large Magellanic Cloud observed with IUE in 1991 and 1992 showed also the possible presence of 7Be and similar yields. For an ejecta of MH, ej = 10-5 M, the amount of 7Li produced is of $M_{^7 Li} = (3.7 \pm 0.6) \times 10^{-10}$ M per nova event. Detailed chemical evolutionary model for the SMC shows that novae could have made an amount of lithium in the SMC corresponding to a fractional abundance of A(Li) ≍ 2.6. Therefore, it is argued that a comparison with the abundance of Li in the SMC, as measured by its interstellar medium, could effectively constrain the amount of the initial abundance of primordial Li, which is currently controversial.

Dates and versions

insu-03719744 , version 1 (11-07-2022)

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Luca Izzo, Paolo Molaro, Gabriele Cescutti, Elias Aydi, Pierluigi Selvelli, et al.. Detection of 7Be II in the Small Magellanic Cloud. Monthly Notices of the Royal Astronomical Society, 2022, 510, pp.5302-5314. ⟨10.1093/mnras/stab3761⟩. ⟨insu-03719744⟩
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