TOPoS: III. An ultra iron-poor CEMP multiple system

Caffau, E. and Bonifacio, P. and Spite, M. and Spite, F. and Monaco, L. and Sbordone, L. and Francois, P. and Gallagher, A. and Plez, B. and Zaggia, S. and Ludwig, H.-G. and Cayrel, R. and Koch, Andreas and Steffen, M. and Salvadori, S. and Klessen, R.S. and Glover, S. and Christlieb, N. (2016) TOPoS: III. An ultra iron-poor CEMP multiple system. Astronomy and Astrophysics, 595. ISSN 1432-0746

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Aims. One of the primary objectives of the TOPoS survey is to search for the most metal-poor stars. Our search has led to the discovery of one of the most iron-poor objects known, SDSS J092912.32+023817.0. This object is a multiple system, in which two components are clearly detected in the spectrum. Methods. We have analysed 16 high-resolution spectra obtained using the UVES spectrograph at the ESO 8.2 m VLT telescope to measure radial velocities and determine the chemical composition of the system. Results. Cross correlation of the spectra with a synthetic template yields a double-peaked cross-correlation function (CCF) for eight spectra, and in one case there is evidence for the presence of a third peak. Chemical analysis of the spectrum obtained by averaging all the spectra for which the CCF showed a single peak found that the iron abundance is [Fe/H]=–4.97. The system is also carbon enhanced with [C/Fe]=+3.91 (A(C) = 7.44). From the permitted oxygen triplet we determined an upper limit for oxygen of [O/Fe]< +3.52 such that C/O > 1.3. We are also able to provide more stringent upper limits on the Sr and Ba abundances ([Sr/Fe] < +0.70, and [Ba/Fe] < +1.46, respectively).

Item Type: Journal Article
Journal or Publication Title: Astronomy and Astrophysics
Uncontrolled Keywords: /dk/atira/pure/subjectarea/asjc/1900/1912
Departments: Faculty of Science and Technology > Physics
ID Code: 82090
Deposited By: ep_importer_pure
Deposited On: 10 Oct 2016 08:18
Refereed?: Yes
Published?: Published
Last Modified: 19 Aug 2019 01:54

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