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Chemical abundance analysis of 19 barium stars | | G. C. Yang
; Y. C. Liang
; M. Spite
; Y. Q. Chen
; G. Zhao
; B. Zhang
; G. Q. Liu
; Y. J. Liu
; N. Liu
; L. C. Deng
; F. Spite
; V. Hill
; C. X. Zhang
; | | Date: |
28 Feb 2016 | | Abstract: | We aim at deriving accurate atmospheric parameters and chemical abundances of
19 barium (Ba) stars, including both strong and mild Ba stars, based on the
high signal-to-noise ratio and high resolution Echelle spectra obtained from
the 2.16 m telescope at Xinglong station of National Astronomical
Observatories, Chinese Academy of Sciences. The chemical abundances of the
sample stars were obtained from an LTE, plane-parallel and line-blanketed
atmospheric model by inputting the atmospheric parameters (effective
temperatures, surface gravities, metallicity and microturbulent velocity) and
equivalent widths of stellar absorption lines. These samples of Ba stars are
giants indicated by atmospheric parameters, metallicities and kinematic
analysis about UVW velocity. Chemical abundances of 17 elements were obtained
for these Ba stars. Their light elements (O, Na, Mg, Al, Si, Ca, Sc, Ti, V, Cr,
Mn and Ni) are similar to the solar abundances. Our samples of Ba stars show
obvious overabundances of neutron-capture (n-capture) process elements relative
to the Sun. Their median abundances of [Ba/Fe], [La/Fe] and [Eu/Fe] are 0.54,
0.65 and 0.40, respectively. The YI and ZrI abundances are lower than Ba, La
and Eu, but higher than the light elements for the strong Ba stars and similar
to the iron-peak elements for the mild stars. There exists a positive
correlation between Ba intensity and [Ba/Fe]. For the n-capture elements (Y,
Zr, Ba, La), there is an anti-correlation between their [X/Fe] and [Fe/H]. We
identify nine of our sample stars as strong Ba stars with [Ba/Fe]>0.6 where
seven of them have Ba intensity Ba=2-5, one has Ba=1.5 and another one has
Ba=1.0. The remaining ten stars are classified as mild Ba stars with
0.17<[Ba/Fe]<0.54. | | Source: | arXiv, 1602.8704 | | Services: | Forum | Review | PDF | Favorites | |
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