Query : 2003A&A...402.1061P

2003A&A...402.1061P - Astronomy and Astrophysics, volume 402, 1061-1071 (2003/5-2)

Spectroscopic analysis of two CH subgiant stars: HD 50264 and HD 87080.


Abstract (from CDS):

We present the abundance pattern of two CH subgiant stars HD 50264 and HD 87080 based on high-resolution optical spectra. We also determined the spectroscopic stellar atmospheric parameters, temperature and microturbulent velocity as well as stellar surface gravity from a solution of excitation and ionization equilibria of FeI and FeII lines under the assumption of local thermodynamic equilibrium. The abundance analysis reveals HD 50264 with a metallicity of [Fe/H]=-0.34 and HD 87080 with a metallicity of [Fe/H]=-0.51. We compare the abundance pattern with abundances of disk stars and also with other stars of the same class. We found that iron group, α-elements, manganese, as well as sodium and aluminum of HD 50264 and HD 87080 follow the abundance pattern of the disk stars. The heavy-element abundance pattern of both stars shows enhancements by a factor of 4-6 with respect to the sun. By heavy-element we mean the elements that have been synthesized by neutron capture, such as barium, yttrium and zirconium. We also discuss the abundances of the s-process elements and compare our results with other binary systems that display enrichment due to neutron-capture reactions, through several diagrams involving the index [hs/ls] and [s/Fe], the metallicity and [C/Fe] ratio. We compare the observed abundance of the heavy elements with theoretical nucleosynthesis calculations. This shows that the s-process are best fit by models in which the seed nuclei are exposed to single neutron irradiation and with a neutron exposure of τ=0.9 and τ=1.0 respectively for HD 50264 and HD 87080. We also use the [Rb/Zr] ratio in order to investigate how this ratio behaves versus metallicity for other binary systems, including HD 50264 and HD 87080 that are s-process enriched.

Abstract Copyright:

Journal keyword(s): stars: chemically peculiar - stars: abundances

Simbad objects: 2

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Number of rows : 2
N Identifier Otype ICRS (J2000)
ICRS (J2000)
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2022
1 HD 50264 SB* 06 51 12.5032525968 -29 34 32.306464056   9.63 9.05     G1.5II-III:_Ba2_CH0.5 49 0
2 HD 87080 SB* 10 02 00.8591714448 -33 41 06.504849924   10.15 9.37     G6III_Ba5.5_CH 49 0

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