12C/13C isotopic ratios in red-giant stars of the open cluster NGC 6791

László Szigeti, Szabolcs Mészáros, Verne V. Smith, Katia Cunha, Nadège Lagarde, Corinne Charbonnel, D. A. García-Hernández, Matthew Shetrone, Marc Pinsonneault, Carlos Allende Prieto, J. G. Fernández-Trincado, József Kovács, Sandro Villanova

Research output: Contribution to journalArticlepeer-review

15 Scopus citations


Carbon isotope ratios, along with carbon and nitrogen abundances, are derived in a sample of 11 red-giant members of one of the most metal-rich clusters in the Milky Way, NGC 6791. The selected red-giants have a mean metallicity and standard deviation of [Fe/H] = +0.39 ± 0.06 (Cunha et al. 2015). We used high-resolution H-band spectra obtained by the SDSS-IV Apache Point Observatory Galactic Evolution Experiment. The advantage of using high-resolution spectra in the H band is that lines of CO are well represented and their line profiles are sensitive to the variation of 12C/13C. Values of the 12C/13C ratio were obtained from a spectrum synthesis analysis. The derived 12C/13C ratios varied between 6.3 and 10.6 in NGC 6791, in agreement with the final isotopic ratios from thermohaline-induced mixing models. The ratios derived here are combined with those obtained for more metal poor red-giants from the literature to examine the correlation between 12C/13C, mass, metallicity, and evolutionary status.

Original languageEnglish (US)
Pages (from-to)4810-4817
Number of pages8
JournalMonthly Notices of the Royal Astronomical Society
Issue number4
StatePublished - Mar 1 2018


  • Stars: abundances
  • Stars: evolution
  • Stars: late-type
  • Stars: low-mass

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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