SPECTROSCOPIC ANALYSIS OF METAL-POOR STARS FROM LAMOST: EARLY RESULTS

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] <...

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Bibliographic Details
Published in:The Astrophysical journal 2015-01, Vol.798 (2), p.1-13
Main Authors: Li, Hai-Ning, Zhao, Gang, Christlieb, Norbert, Wang, Liang, Wang, Wei, Zhang, Yong, Hou, Yonghui, Yuan, Hailong
Format: Article
Language:English
Subjects:
Abundance
ASTROPHYSICS, COSMOLOGY AND ASTRONOMY
C (programming language)
CARBON
COMPARATIVE EVALUATIONS
COSMOCHEMISTRY
Deviation
ELECTROMAGNETIC PULSES
GALACTIC EVOLUTION
GALAXIES
IRON
Metallicity
NITROGEN
NUCLEOSYNTHESIS
Pilots
POTENTIALS
R PROCESS
RESOLUTION
Spectra
STARS
TELESCOPES
TRITIUM
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Summary: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. 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 [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.
ISSN:1538-4357
0004-637X
1538-4357
DOI:10.1088/0004-637X/798/2/110