Isotopic ratios in the red giant component of the recurrent nova T coronae borealis

Y. V. Pavlenko, A. Evans, D. P.K. Banerjee, T. R. Geballe, U. Munari, R. D. Gehrz, C. E. Woodward, S. Starrfield

Research output: Contribution to journalArticlepeer-review

Abstract

We report the determination of abundances and isotopic ratios for C, O, and Si in the photosphere of the red giant (RG) component of the recurrent nova (RN) 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 RG interior which are brought to the surface during dredge-up and (ii) contamination of the RG, either during the common envelope phase of the binary evolution or by material synthesized in RN 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 an RG 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 RG evolution (∼550) or from contamination of the RG 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 an RN system of contamination by ejecta having anomalous abundances and isotopic ratios.

Original languageEnglish (US)
Pages (from-to)4853-4863
Number of pages11
JournalMonthly Notices of the Royal Astronomical Society
Volume498
Issue number4
DOIs
StatePublished - Nov 1 2020

Keywords

  • Abundances
  • Cataclysmic variables
  • Infrared: stars
  • Novae
  • Nuclear reactions
  • Nucleosynthesis
  • Stars: AGB and post-AGB
  • Stars: abundances
  • Stars: individual: (T CrB)

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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