HD 209621: Abundances of neutron-capture elements

TL;DR

This study uses high-resolution spectra to determine the detailed elemental abundances of HD 209621, revealing significant enhancements in neutron-capture and s-process elements, and clarifying the star's nucleosynthetic origins.

Contribution

It provides updated stellar parameters and detailed abundance patterns for multiple heavy elements, including the first estimates for several neutron-capture elements in HD 209621.

Findings

HD 209621 has a metallicity of [Fe/H] = -1.93.

The star shows large enhancements in carbon and heavy elements.

The neutron-capture elements are primarily produced by the s-process.

Abstract

High resolution spectra obtained from the Subaru Telescope High Dispersion Spectrograph have been used to update the stellar atmospheric parameters and metallicity of the star HD 209621. We have derived a metallicity of [Fe/H] = -1.93 for this star, and have found a large enhancement of carbon and of heavy elements, with respect to iron. Updates on the elemental abundances of four s-process elements (Y, Ce, Pr, Nd) along with the first estimates of abundances for a number of other heavy elements (Sr, Zr, Ba, La, Sm, Eu, Er, Pb) are reported. The stellar atmospheric parameters, the effective temperature, Teff, and the surface gravity, log g (4500 K, 2.0), are determined from LTE analysis using model atmospheres. Estimated [Ba/Eu] = +0.35, places the star in the group of CEMP-(r+s) stars; however, the s-elements abundance pattern seen in HD 209621 is characteristic of CH stars; notably, the 2nd-peak s-process elements are more enhanced than the first peak s-process elements. HD 209621 is also found to show a large enhancement of the 3rd-peak s-process element lead (Pb) with [Pb/Fe] = +1.88. The relative contributions of the two neutron-capture processes, r- and s- to the observed abundances are examined using a parametric model based analysis, that hints that the neutron-capture elements in HD 209621 primarily originate in s-process.