Evans, A ORCID: https://orcid.org/0000-0002-3142-8953, Pavlenko, YA, Banerjee, DPK, Geballe, TR, Munari, U, Gehrz, RD, Woodward, CE and Starrfield, S (2020) Isotopic ratios in the red giant component of the recurrent nova T Coronae Borealis. Monthly Notices of the Royal Astronomical Society.

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Abstract

We report the determination of abundances and isotopic ratios for C, O and Si in the photosphere of the red giant component of the recurrent nova T Coronae Borealis from new 2.284–2.402 µm and 3.985–4.155 µm spectroscopy. Abundances and isotopic ratios in the photosphere may be affected by (i) processes in the red giant interior which are brought to the surface during dredge-up, (ii) contamination of the red giant, either during the common envelope phase of the binary evolution or by material synthesised in recurrent nova eruptions, or a combination of the two. We find that the abundances of C, O and Si are reasonably consistent with the expected composition of a red giant after first dredge-up, as is the 16O/17O ratio. The 28Si/29Si ratio is found to be 8.6 ± 3.0, and that for 28Si/30Si is 21.5 ± 3.0. The 12C/13C ratio (10 ± 2) is somewhat lower than expected for first dredge-up. The 16O/18O ratio (41 ± 3) is highly inconsistent with that expected either from red giant evolution (∼ 550) or from contamination of the red giant by the products of a nova thermonuclear runaway. In particular the C and O isotopic ratios taken in combination are a puzzle. We urge confirmation of our results using spectroscopy at high resolution. We also encourage a thorough theoretical study of the effects on the secondary star in a recurrent nova system of contamination by ejecta having anomalous abundances and isotopic ratios.

Item Type: Article
Additional Information: © 2020 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/open_access/funder_policies/chorus/standard_publication_model) The final version of this article can be found online with any extra information at; https://academic.oup.com/mnras/advance-article-abstract/doi/10.1093/mnras/staa2658/5902859?redirectedFrom=fulltext
Uncontrolled Keywords: nuclear reactions, nucleosynthesis, abundances — stars: AGB and post-AGB — stars: abundances — stars: individual (T CrB) — novae: cataclysmic variables — infrared: stars
Subjects: Q Science > Q Science (General)
Q Science > QA Mathematics
Q Science > QB Astronomy
Q Science > QB Astronomy > QB460 Astrophysics
Q Science > QB Astronomy > QB600 Planets. Planetology
Q Science > QB Astronomy > QB799 Stars
Divisions: Faculty of Natural Sciences > School of Chemical and Physical Sciences
Depositing User: Symplectic
Date Deposited: 02 Sep 2020 14:57
Last Modified: 15 Sep 2020 15:49
URI: https://eprints.keele.ac.uk/id/eprint/8606

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