Spectroscopic validation of low-metallicity stars from rave
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2018
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We present results from a medium-resolution (R ∼ 2000) spectroscopic follow-up campaign of 1694 bright
(V < 13.5), very metal-poor star candidates from the RAdial Velocity Experiment (RAVE). Initial selection of the
low-metallicity targets was based on the stellar parameters published in RAVE Data Releases 4 and 5. Follow up
was accomplished with the Gemini-N and Gemini-S, the ESO/NTT, the KPNO/Mayall, and the SOAR
telescopes. The wavelength coverage for most of the observed spectra allows for the determination of carbon and
α-element abundances, which are crucial for considering the nature and frequency of the carbon-enhanced metal poor (CEMP) stars in this sample. We find that 88% of the observed stars have Fe H [ ] −1.0, 61% have
Fe H [ ] −2.0, and 3% have Fe H [ ] −3.0 (with four stars at Fe H [ ] −3.5). There are 306 CEMP star
candidates in this sample, and we identify 169 CEMP Group I, 131 CEMP Group II, and 6 CEMP Group III stars
from the A(C) versus [Fe/H] diagram. Inspection of the a C [ ] abundance ratios reveals that five of the CEMP
Group II stars can be classified as “mono-enriched second-generation” stars. Gaia DR1 matches were found for
734 stars, and we show that transverse velocities can be used as a confirmatory selection criteria for low-metallicity
candidates. Selected stars from our validated list are being followed-up with high-resolution spectroscopy to reveal
their full chemical-abundance patterns for further studies.
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PLACCO, Vinicius M. et al. Spectroscopic validation of low-metallicity stars from rave. The Astronomical Journal, Bristol, v. 155, n. 6, e256, 2018. DOI: 10.3847/1538-3881/aac20c. Disponível em: https://iopscience.iop.org/article/10.3847/1538-3881/aac20c. Acesso em: 11 maio 2023.