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

E. Caffau, P. Bonifacio, M. Spite, F. Spite, L. Monaco, L. Sbordone, P. François, A. J. Gallagher, B. Plez, S. Zaggia, H. G. Ludwig, R. Cayrel, A. Koch, M. Steffen, S. Salvadori, R. Klessen, S. Glover, N. Christlieb

Research output: Contribution to journalArticlepeer-review

15 Citations (Scopus)

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).

Original languageEnglish
Article numberL6
JournalAstronomy and Astrophysics
Volume595
DOIs
Publication statusPublished - 1 Nov 2016

Keywords

  • Binaries: spectroscopic
  • Galaxy: abundances
  • Galaxy: formation
  • Galaxy: halo
  • Stars: Population II
  • Stars: abundances

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

Fingerprint

Dive into the research topics of 'TOPoS: III. An ultra iron-poor multiple CEMP system ?'. Together they form a unique fingerprint.

Cite this