The R-Process Alliance: Analysis of Limited-r Stars

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Hauptverfasser: Xylakis-Dornbusch, T., Hansen, T. T., Beers, T. C., Christlieb, N., Ezzeddine, R., Frebel, A., Holmbeck, E., Placco, V. M., Roederer, I. U., Sakari, C. M., Sneden, C.
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Veröffentlicht: 2024
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author Xylakis-Dornbusch, T.
Hansen, T. T.
Beers, T. C.
Christlieb, N.
Ezzeddine, R.
Frebel, A.
Holmbeck, E.
Placco, V. M.
Roederer, I. U.
Sakari, C. M.
Sneden, C.
author_facet Xylakis-Dornbusch, T.
Hansen, T. T.
Beers, T. C.
Christlieb, N.
Ezzeddine, R.
Frebel, A.
Holmbeck, E.
Placco, V. M.
Roederer, I. U.
Sakari, C. M.
Sneden, C.
contents Context. In recent years, the R-Process Alliance (RPA) has conducted a successful search for stars enhanced in elements produced by the rapid neutron-capture (r-)process. In particular, the RPA has uncovered a number of stars strongly enriched in light r-process elements, such as Sr, Y and Zr, the so-called limited-r stars, in order to investigate the astrophysical production site(s) of these elements. Aims. With this paper, we aim to investigate the possible formation sites for light neutron-capture elements, by deriving detailed abundances for neutron-capture elements from high-resolution, high signal-to-noise spectra of three limited-r stars. Methods. We conducted a 1D local thermodynamic equilibrium spectroscopic abundance analysis of three stars, as well as a kinematic analysis. Further, we calculated the lanthanide mass fraction (XLa) of our stars and of limited-r stars from the literature. Results. We found that the neutron-capture element abundance pattern of limited-r stars behaves differently depending on their [Ba/Eu]] ratios, and suggest that this should be taken into account in future investigations of their abundances. Furthermore, we found that the XLa of limited-r stars is lower than that of the kilonova AT2017gfo. The latter seems to be in the transition zone between limited-r XLa and that of r-I, r-II stars. Finally, we found that, unlike r-I and r-II stars, the current sample of limited-r stars are largely born in the Galaxy rather than being accreted.
format Preprint
id arxiv_https___arxiv_org_abs_2404_03379
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle The R-Process Alliance: Analysis of Limited-r Stars
Xylakis-Dornbusch, T.
Hansen, T. T.
Beers, T. C.
Christlieb, N.
Ezzeddine, R.
Frebel, A.
Holmbeck, E.
Placco, V. M.
Roederer, I. U.
Sakari, C. M.
Sneden, C.
Solar and Stellar Astrophysics
Astrophysics of Galaxies
Context. In recent years, the R-Process Alliance (RPA) has conducted a successful search for stars enhanced in elements produced by the rapid neutron-capture (r-)process. In particular, the RPA has uncovered a number of stars strongly enriched in light r-process elements, such as Sr, Y and Zr, the so-called limited-r stars, in order to investigate the astrophysical production site(s) of these elements. Aims. With this paper, we aim to investigate the possible formation sites for light neutron-capture elements, by deriving detailed abundances for neutron-capture elements from high-resolution, high signal-to-noise spectra of three limited-r stars. Methods. We conducted a 1D local thermodynamic equilibrium spectroscopic abundance analysis of three stars, as well as a kinematic analysis. Further, we calculated the lanthanide mass fraction (XLa) of our stars and of limited-r stars from the literature. Results. We found that the neutron-capture element abundance pattern of limited-r stars behaves differently depending on their [Ba/Eu]] ratios, and suggest that this should be taken into account in future investigations of their abundances. Furthermore, we found that the XLa of limited-r stars is lower than that of the kilonova AT2017gfo. The latter seems to be in the transition zone between limited-r XLa and that of r-I, r-II stars. Finally, we found that, unlike r-I and r-II stars, the current sample of limited-r stars are largely born in the Galaxy rather than being accreted.
title The R-Process Alliance: Analysis of Limited-r Stars
topic Solar and Stellar Astrophysics
Astrophysics of Galaxies
url https://arxiv.org/abs/2404.03379