High-resolution spectroscopic observations of the metal-poor, chemically peculiar, and high velocity Fehrenbach & Duflot star⋆,⋆⋆
Sobolev Astronomical Institute, St. Petersburg State University, Universitetski pr. 28, St. Petersburg 198504, Russia
2 Observatório Nacional, Rua José Cristino, 77, CEP 20921-400, São Cristóvão, Rio de Janeiro-RJ, Brazil
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Received: 6 February 2010
Accepted: 5 May 2011
Aims. We determine the atmospheric parameters and abundance pattern of the chemically peculiar metal-poor Fehrenbach & Duflot (Feh-Duf) star to more clearly understand its evolutionary state and the nature of the s-element enhancement in this star.
Methods. Its atmospheric parameters and chemical abundances were determined using high resolution optical spectroscopy and employing the local-thermodynamic-equilibrium model atmospheres of Kurucz and spectral analysis code MOOG.
Results. The derived abundances show that the Feh-Duf star is a low-metallicity ([Fe/H] = −1.93) star with high carbon and heavy s-element abundances, while the abundance of the light s-process element yttrium is low ([Y/Fe] = −0.07). The oxygen abundance is lower than for Galactic halo stars of similar metallicity.We conclude that the Feh-Duf star could be a CH star with C/O = 1.3. Another possibility is that the Feh-Duf star could be an early-AGB star. The Fehrenbach & Duflot star is also a lead star with [Pb/Ce] = +0.69. In addition, it displays an extreme retrograde motion (VGRF = −259 km s-1), which in combination with its underabundance of α-elements suggests that this star may have been captured by the Milky Way galaxy.
Key words: stars: abundances / stars: individual: Feh-Duf / stars: chemically peculiar / stars: population II / stars: kinematics and dynamics / stars: fundamental parameters
© ESO, 2011