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Detection of 7Be ii in the Small Magellanic Cloud

Izzo, L, Molaro, P, Cescutti, G, Aydi, E, Selvelli, P, Harvey, E, Agnello, A, Bonifacio, P, Della Valle, M, Guido, E and Hernanz, M (2021) Detection of 7Be ii in the Small Magellanic Cloud. Monthly Notices of the Royal Astronomical Society, 510 (4). pp. 5302-5314. ISSN 0035-8711

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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.

Item Type: Article
Additional Information: This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society ©: 2021 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.
Uncontrolled Keywords: 0201 Astronomical and Space Sciences; Astronomy & Astrophysics
Subjects: Q Science > QB Astronomy
Divisions: Astrophysics Research Institute
Publisher: Oxford University Press (OUP)
SWORD Depositor: A Symplectic
Date Deposited: 11 Oct 2022 14:37
Last Modified: 11 Oct 2022 14:45
DOI or ID number: 10.1093/mnras/stab3761
URI: https://researchonline.ljmu.ac.uk/id/eprint/17811
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