Speaker
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A POSSIBLE NUCLEAR SOLUTION TO THE 18F DEFICIENCY IN NOVAE
M. La Cognata1, R. G. Pizzone1, J. José2,3, M. Hernanz3,4, S. Cherubini1,5, M. Gulino1,6, G. G. Rapisarda1,5, and C. Spitaleri1,5
1 INFN - Laboratori Nazionali del Sud, Catania, Italy
2 Departament de Física, EEBE, Universitat Politècnica de Catalunya, E-08019 Barcelona, Spain
3 Institut d’Estudis Espacials de Catalunya, E-08034 Barcelona, Spain
4 Institut de Ciencies de l’Espai (ICE-CSIC). Campus UAB. c/ Can Magrans s/n, E-08193 Bellaterra, Spain
5 Dipartimento di Fisica e Astronomia, Università degli Studi di Catania, Catania, Italy
6 Facoltà di Ingegneria ed Architettura, Kore University, Viale delle Olimpiadi, 1, I-94100 Enna, Italy
Crucial information on nova nucleosynthesis can be potentially inferred from γ-ray signals powered by 18F decay [1]. Therefore, the reaction network producing and destroying this radioactive isotope has been extensively studied in the last years. Among those reactions, the 18F(p,α)15O cross-section has been measured by means of several dedicated experiments, both using direct and indirect methods. The presence of interfering resonances in the energy region of astrophysical interest has been reported by many authors including the recent applications of the Trojan Horse Method (THM). The THM is an indirect method using direct reactions to populate 19Ne states of astrophysical importance, with no suppression by the Coulomb and centrifugal barriers. In this work, we evaluate what changes are introduced by the Trojan Horse data [2-4] in the 18F(p,α)15O astrophysical factor recommended in a recent R-matrix analysis, accounting for existing direct and indirect measurements [5]. We will particularly focus on the role of the THM experiment, since it allowed us to cover the 0-1 MeV energy range with experimental data, with no need of extrapolation and with unprecedented accuracy. Then, the updated reaction rate is calculated and parameterized and implications of the new results on nova nucleosynthesis are thoroughly discussed. In particular, while no change on the dynamical properties of the explosion is found due to the revised reaction rate, important differences in the chemical composition of the ejected matter is observed, with a net reduction in the mean 18F content by a factor of 2 and a corresponding increase in the detectability distance [4].
[1] J. José, Stellar Explosions: Hydrodynamics and Nucleosynthesis (Boca Raton, FL, London: CRC/Taylor and Francis, 2016)
[2] R. G. Pizzone et al., Eur. Phys. J. A, 52 (2016) 24
[3] S. Cherubini et al., Physical Review C, 92 (2015) 015805
[4] M. La Cognata et al., The Astrophysical Journal, 846 (2017) 65
[5] D. W. Bardayan et al. 2015, Phys. Lett. B, 751, (2015) 311
