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- Title
New ultra metal-poor stars from SDSS: follow-up GTC medium-resolution spectroscopy.
- Authors
Aguado, D. S.; Prieto, C. Allende; Hernández, J. I. González; Rebolo, R.; Caffau, E.
- Abstract
Context. The first generation of stars formed in the Galaxy left behind the chemical signatures of their nucleosynthesis in the interstellar medium, visible today in the atmospheres of low-mass stars that formed afterwards. Sampling the chemistry of those low-mass provides insight into the first stars. Aims. We aim to increase the samples of stars with extremely low metal abundances, identifying ultra metal-poor stars from spectra with modest spectral resolution and signal-to-noise ratio (S/N). Achieving this goal involves deriving reliable metallicities and carbon abundances from such spectra. Methods. We carry out follow-up observations of faint, V > 19, metal-poor candidates selected from SDSS spectroscopy and observed with the Optical System for Imaging and low-Intermediate-Resolution Integrated Spectroscopy (OSIRIS) at GTC. The SDSS and follow-up OSIRIS spectra were analyzed using the FERRE code to derive effective temperatures, surface gravities, metallicities and carbon abundances. In addition, a well-known extremely metal-poor star has been included in our sample to calibrate the analysis methodology. Results. We observed and analyzed five metal-poor candidates from modest-quality SDSS spectra. All stars in our sample have been confirmed as extremely metal-poor stars, in the [Fe/H] < -3.3 regime. We report the recognition of J173403+644632, a carbon- enhanced ultra metal-poor dwarf star with [Fe/H] = -4.3 and [C/Fe] = +3.1.
- Subjects
GALAXIES; NUCLEOSYNTHESIS; LOW mass stars; SIGNAL-to-noise ratio; STARS
- Publication
Astronomy & Astrophysics / Astronomie et Astrophysique, 2017, Vol 604, p1
- ISSN
0004-6361
- Publication type
Article
- DOI
10.1051/0004-6361/201731320