Equivalent widths of LAMOST metal-poor stars Virtual Observatory Resource

Authors
  1. Li H.-N.
  2. Zhao G.
  3. Christlieb N.
  4. Wang L.
  5. Wang W.
  6. Zhang Y.
  7. Hou Y.,Yuan H.
  8. Published by
    CDS
Abstract

We report on early results from a pilot program searching for metal-poor stars with LAMOST and follow-up high-resolution observation acquired with the MIKE spectrograph attached to the Magellan II telescope. We performed detailed abundance analysis for eight objects with iron abundances [Fe/H]<-2.0, including five extremely metal-poor (EMP; [Fe/H]<-3.0) stars with two having [Fe/H]<-3.5. Among these objects, three are newly discovered EMP stars, one of which is confirmed for the first time with high-resolution spectral observations. Three program stars are regarded as carbon-enhanced metal-poor (CEMP) stars, including two stars with no enhancement in their neutron-capture elements, which thus possibly belong to the class of CEMP-no stars; one of these objects also exhibits significant enhancement in nitrogen, and is thus a potential carbon and nitrogen-enhanced metal-poor star. The [X/Fe] ratios of the sample stars generally agree with those reported in the literature for other metal-poor stars in the same [Fe/H] range. We also compared the abundance patterns of individual program stars with the average abundance pattern of metal-poor stars and find only one chemically peculiar object with abundances of at least two elements (other than C and N) showing deviations larger than 0.5 dex. The distribution of [Sr/Ba] versus [Ba/H] agrees that an additional nucleosynthesis mechanism is needed aside from a single r-process. Two program stars with extremely low abundances of Sr and Ba support the prospect that both main and weak r-processes may have operated during the early phase of Galactic chemical evolution. The distribution of [C/N] shows that there are two groups of carbon-normal giants with different degrees of mixing. However, it is difficult to explain the observed behavior of the [C/N] of the nitrogen-enhanced unevolved stars based on current data.

Keywords
  1. chemical-abundances
  2. line-intensities
  3. radial-velocity
  4. chemically-peculiar-stars
Bibliographic source Bibcode
2015ApJ...798..110L
See also HTML
https://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/798/110
IVOA Identifier IVOID
ivo://CDS.VizieR/J/ApJ/798/110
Document Object Identifer DOI
doi:10.26093/cds/vizier.17980110

Access

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http://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/798/110
https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/798/110
http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/798/110
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https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/798/110/stars?
http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/798/110/stars?

History

2015-06-18T13:12:30Z
Resource record created
2015-06-18T13:12:30Z
Created
2017-07-06T06:26:07Z
Updated

Contact

Name
CDS support team
Postal Address
CDS, Observatoire de Strasbourg, 11 rue de l'Universite, F-67000 Strasbourg, France
E-Mail
cds-question@unistra.fr