Searching for R-process-enhanced Stars in the LAMOST Survey. II. Two New r-II Stars in the Milky Way Disk

Xie, Xiao-Jin; Shi, Jianrong; Yan, Hong-Liang; Chen, Tian-Yi; Allende Prieto, Carlos; Beers, Timothy C.; Jin, Shi-Lun; Liu, Shuai; Li, Chun-Qian; Zhou, Ze-Ming; Ding, Ming-Yi; Tang, Yao-Jia
Bibliographical reference

The Astrophysical Journal

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5
2025
Number of authors
12
IAC number of authors
1
Citations
1
Refereed citations
0
Description
R-process-enhanced (RPE) stars are rare and typically metal-poor ([Fe/H] < ‑1.0), primarily found in the Milky Way halo system and dwarf galaxies. This study reports the discovery of two relatively bright, highly RPE stars ([Eu/Fe] > +0.70) located in the Milky Way disk, with [Fe/H] of ‑0.34 and ‑0.80, respectively. These two stars are selected from the Large Sky Area Multi-Object Fiber Spectroscopic Telescope medium-resolution (R ∼ 7500) spectroscopic survey. Follow-up high-resolution (R ∼ 25,000) observations were conducted with the High Optical Resolution Spectrograph installed on the 10.4 m Gran Telescopio Canarias. We perform the determination of elemental abundances and calculate the orbital parameters. We find that they are r-II stars with elemental abundances in agreement with the solar r-process pattern. These two objects are chemically and dynamically consistent with membership in the Galactic disk and exhibit no evidence of being part of accreted systems.
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Stellar spectroscopy allows us to determine the properties and chemical compositions of stars. From this information for stars of different ages in the Milky Way, it is possible to reconstruct the chemical evolution of the Galaxy, as well as the origin of the elements heavier than boron, created mainly in stellar interiors. It is also possible to
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Allende Prieto