S1242: a lithium-rich subgiant star in the open cluster M 67

• Autor(a) principal: Martins, B. L. Canto
• Data de Publicação: 2006
• Outros Autores: Lèbre, A., Laverny, P. de, Melo, C. H. F., Nascimento Jr, J. D. do, Richard, O., Medeiros, José Renan de
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Institucional da UFRN
• Texto Completo: https://repositorio.ufrn.br/jspui/handle/123456789/28986
• topic: Stars: binaries: general; Stars: abundances; Stars: fundamental parameters; Stars: atmospheres; Stars: evolution

Aims. We report the serendipitous discovery of a lithium-rich subgiant star, S1242. This object is member of a large eccentricity spectroscopic binary system in the solar-age open cluster M 67. Methods. Using VLT/FLAMES-UVES observations and synthetic spectrum analysis, we derived for this star stellar parameters (temperature, gravity, metallicity and rotational velocity) and a surface Li abundance (ALi = 2.7) larger than the higher abundance of M 67 stars near the turn-off. Results. The high Li abundance we found in S1242 points to an excess of lithium at the subgiant stage. We discuss two possible explanations for this unusually high Li content in this binary system: a preservation of the Li at the turn-off stage due to tidal effects, or an efficient dredge-up of Li, hidden below the convective zone by atomic diffusion occuring in the post turn-off stage.