Discovery of a strongly r-process enhanced extremely metal-poor star LAMOST J110901.22+075441.8. (August 2015)

• Record Type: Journal Article
• Authors: Li, Hai-Ning; Aoki, Wako; Honda, Satoshi; Zhao, Gang; Christlieb, Norbert; Suda, Takuma
• Is Part Of: Research in astronomy and astrophysics. Volume 15:Number 8(2015:Aug.)
• Page Start: 1264
• Page End: 1274
• Publication Date: 2015-08
• Subjects: Astronomy -- Periodicals; Astrophysics -- Periodicals; 520.5
• DOI: 10.1088/1674-4527/15/8/011
• Languages: English
• ISSNs: 1674-4527

Abstract

<abstract> <title>Abstract</title> <p>We report the discovery of an extremely metal-poor (EMP) giant, LAMOST J110901.22+075441.8, which exhibits a large excess of <italic>r</italic>-process elements with [Eu/Fe] ∼ +1.16. The star is one of the newly discovered EMP stars identified from the LAMOST low-resolution spectroscopic survey and a high-resolution follow-up observation with the Subaru Telescope. Stellar parameters and elemental abundances have been determined from the Subaru spectrum. Accurate abundances for a total of 23 elements including 11 neutron-capture elements from Sr through Dy have been derived for LAMOST J110901.22+075441.8. The abundance pattern of LAMOST J110901.22+075441.8 in the range of C through Zn is in line with the "normal" population of EMP halo stars, except that it shows a notable underabundance in carbon. The heavy element abundance pattern of LAMOST J110901.22+075441.8 is in agreement with other well studied cool <italic>r</italic>−II metal-poor giants such as CS 22892–052 and CS 31082–001. The abundances of elements in the range from Ba through Dy match the scaled solar <italic>r</italic>-process pattern well. LAMOST J110901.22+075441.8 provides the first detailed measurements of neutron-capture elements among <italic>r</italic>–II stars at such low metallicity with [Fe/H] ≲ −3.4, and exhibits similar behavior as other <italic>r</italic>–II stars in the abundance ratio of Zr/Eu as well as Sr/Eu and Ba/Eu.</p> </abstract>