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http://hdl.handle.net/20.500.12386/32530
Titolo: | TOPoS. III. An ultra iron-poor multiple CEMP system | Autori: | Caffau, E. Bonifacio, P. Spite, M. Spite, F. Monaco, L. Sbordone, L. François, P. Gallagher, A. J. Plez, B. ZAGGIA, Simone Ludwig, H. -G. Cayrel, R. Koch, A. Steffen, M. Salvadori, S. Klessen, R. Glover, S. Christlieb, N. |
Data pubblicazione: | 2016 | Rivista: | ASTRONOMY & ASTROPHYSICS | Numero: | 595 | Da pagina:: | L6 | Abstract: | 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). Based on observations made with ESO Telescopes at the La Silla Paranal Observatory under programme ID 094.D-0488 and 096.D-0616. | URI: | http://hdl.handle.net/20.500.12386/32530 | URL: | https://www.aanda.org/articles/aa/full_html/2016/11/aa29776-16/aa29776-16.html | ISSN: | 0004-6361 | DOI: | 10.1051/0004-6361/201629776 | Bibcode ADS: | 2016A&A...595L...6C | Fulltext: | open |
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