Discovery of an Extremely r-process-enhanced Thin-disk Star with [Eu/H] = +0.78
Year: 2024
Type: article
Abstract: Highly r-process-enhanced (RPE) stars are rare and usually metal poor ([Fe/H] < −1.0), and they mainly populate the Milky Way halo and dwarf galaxies. This study presents the discovery of a relatively bright (V = 12.72), highly RPE (r-II) star ([Eu/Fe] = +1.32, [Ba/Eu] = −0.95), LAMOST J020623.21+494127.9. This star was 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 Gran Telescopio Canarias. The stellar parameters (T eff = 4130 K, log g = 1.52, [Fe/H] = −0.54, ξ = 1.80 km s−1) have been inferred taking into account nonlocal thermodynamic equilibrium effects. The abundances of [Ce/Fe], [Pr/Fe], and [Nd/Fe] are +0.19, +0.65, and +0.64, respectively, relatively low compared to the Solar r-process pattern normalized to Eu. This star has a high metallicity ([Fe/H] = −0.54) compared to most other highly RPE stars and has the highest measured abundance ratio of Eu to H ([Eu/H] = +0.78). It is classified as a thin-disk star based on its kinematics and does not appear to belong to any known stream or dwarf galaxy.
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $2,400
Funders: National Science Foundation, Joint Institute for Nuclear Astrophysics - Center for the Evolution of the Elements, National Natural Science Foundation of China, Chinese Academy of Sciences, Youth Innovation Promotion Association of the Chinese Academy of Sciences, Ministerio de Ciencia e Innovación, National Development and Reform Commission, Instituto de Astrofísica de Canarias, Youth Innovation Promotion Association, National Astronomical Observatories, Chinese Academy of Sciences, Office of International Science and Engineering
Awards: JINA Center for the Evolution of the Elements, G1682633203, G1807621157, G1962401841, G2290926408, G2695431083, G317434862, AccelNet-WOU: International Research Network for Nuclear Astrophysics (IReNA), G3661801348, G3828723390, G4025223823, G425872791, G5805502524, G6586359471, G7082738492, G7170549485, G7457237189, G7843896931
OpenAlex ID: W4400937787