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

Advertised on:
5
2025
Number of authors
12
IAC number of authors
1
Citations
0
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.