4.7 Article

High-resolution spectroscopic analysis of four new chemically peculiar stars

Journal

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
Volume 518, Issue 4, Pages 5414-5443

Publisher

OXFORD UNIV PRESS
DOI: 10.1093/mnras/stac3378

Keywords

nuclear reactions; nucleosynthesis; abundances; stars: abundances; stars: AGB and post-AGB; stars: chemically peculiar; stars: evolution; stars: fundamental parameters

Ask authors/readers for more resources

We present detailed chemical compositions of four chemically peculiar stars on the first-ascent red giant branch, which lack high spectral resolution comprehensive analyses. These stars, BD+03 degrees 2688, HE 0457-1805, HE 1255-2324, and HE 2207-1746, exhibit a range in Galactic population membership with metallicities of [Fe/H] = -1.21, -0.19, -0.31, and -0.55, respectively. We obtained elemental abundances for 28 elements, including CNO group and C-12/C-13 ratios, as well as novel results for the heavy elements tungsten and thallium. All four stars show significant enhancements of neutron-capture elements, indicating enrichments from the slow neutron capture (s-process).
We present detailed chemical compositions of four stars on the first-ascent red giant branch that are classified as chemically peculiar, but lack comprehensive analyses at high spectral resolution. For BD+03 degrees 2688, HE 0457-1805, HE 1255-2324, and HE 2207-1746, we derived metallicities [Fe/H] = -1.21, -0.19, -0.31, and -0.55, respectively, indicating a range in Galactic population membership. In addition to atmospheric parameters, we extracted elemental abundances for 28 elements, including the evolutionary-sensitive CNO group and C-12/C-13 ratios. Novel results are also presented for the heavy elements tungsten and thallium. All four stars have very large enhancements of neutron-capture elements, with high [La/Eu] ratios indicating enrichments from the slow neutron capture (s-process). To interpret these abundances, all indicative of [s/Fe] >1.0, we compared our results with data from literature, as well as with predictions from the Monash and fruity s-process nucleosynthesis models. BD+03 degrees 2688, HE 1255-2324, and HE 2207-1746 show C/O >1, while HE 0457-1805 has C/O <1. Since HE 0457-1805 and HE 1255-2324 are binary stars, their peculiarities are attributable to mass transfer. We identified HE 0457-1805 as a new barium giant star, and HE 1255-2324 as a new CH star, in fact a higher metallicity analogue CEMP-r/s star; the single object reported in literature so far with similar characteristics is the barium star HD 100503 ([Fe/H] = -0.72). A systematic monitoring is needed to confirm the binary nature of BD+03 degrees 2688 and HE 2207-1746, which are probably CH stars.

Authors

I am an author on this paper
Click your name to claim this paper and add it to your profile.

Reviews

Primary Rating

4.7
Not enough ratings

Secondary Ratings

Novelty
-
Significance
-
Scientific rigor
-
Rate this paper

Recommended

No Data Available
No Data Available