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Title: OLD PUZZLE, NEW INSIGHTS: A LITHIUM-RICH GIANT QUIETLY BURNING HELIUM IN ITS CORE

About 1% of giant stars have been shown to have large surface Li abundances, which is unexpected according to standard stellar evolution models. Several scenarios for lithium production have been proposed, but it is still unclear why these Li-rich giants exist. A missing piece in this puzzle is the knowledge of the exact stage of evolution of these stars. Using low- and-high-resolution spectroscopic observations, we have undertaken a survey of lithium-rich giants in the Kepler field. In this Letter, we report the finding of the first confirmed Li-rich core-helium-burning giant, as revealed by asteroseismic analysis. The evolutionary timescales constrained by its mass suggest that Li production most likely took place through non-canonical mixing at the RGB tip, possibly during the helium flash.
Authors:
; ;  [1] ;  [2] ;  [3] ;  [4] ;  [5] ;  [6] ;  [7] ;  [8] ;  [9] ; ;  [10]
  1. Stellar Astrophysics Centre, Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, DK-8000 Aarhus C (Denmark)
  2. Lund Observatory, Department of Astronomy and Theoretical Physics, Box 43, SE-221 00 Lund (Sweden)
  3. Max-Planck-Institut für Sonnensystemforschung, Justus-von-Liebig-Weg 3, D-37077 Göttingen (Germany)
  4. INAF-Astronomical Observatory of Teramo, Via M. Maggini sn, I-64100 Teramo (Italy)
  5. Department of Physics and Meteorology, Indian Institute of Technology, Kharagpur 721302 (India)
  6. Max-Planck-Institut für Astrophysics, Karl Schwarzschild Strasse 1, D-85748 Garching (Germany)
  7. Homi Bhabha Centre for Science Education, TIFR, V. N. Purav Marg, Mankhurd, Mumbai 400088 (India)
  8. LESIA Observatoire de Paris, CNRS, Université Pierre et Marie Curie, Université Denis Diderot, F-92195 Meudon Cedex (France)
  9. Sydney Institute for Astronomy, School of Physics, University of Sydney, NSW 2006 (Australia)
  10. Instituut voor Sterrenkunde, KU Leuven, Celestijnenlaan 200D, B-3001 Leuven (Belgium)
Publication Date:
OSTI Identifier:
22365958
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal Letters; Journal Volume: 784; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; GIANT STARS; HELIUM; HELIUM BURNING; LITHIUM; MASS; OSCILLATIONS; RESOLUTION; STAR EVOLUTION; STAR MODELS; SURFACES