スダ　タクマ   Takuma SUDA   須田　拓馬    所属   学環 教養学環    職種   准教授
言語種別	英語
発行・発表の年月	2021/12
形態種別	学術論文
査読	査読あり
標題	Detailed investigation of two high-speed evolved Galactic stars
執筆形態	共著
掲載誌名	Astronomische Nachrichten
掲載区分	国外
出版社・発行元	Wiley Online Library
巻・号・頁	343,pp.e210032
国際共著	国際共著
著者・共著者	Aroa del Mar Matas Pinto, Elisabetta Caffau, Patrick François, Monique Spite, Piercarlo Bonifacio, Shinya Wanajo, Wako Aoki, Lorenzo Monaco, Takuma Suda, François Spite, Luca Sbordone, Linda Lombardo, Alessio Mucciarelli
概要	The study of metal poor stars provides clarification and knowledge about the primordial Universe. Specially, halo stars provide explanations of the nature of the first generations of stars and the nucleosynthesis in the metal-poor regime. We present a detailed chemical analysis and determination of the kinematic and orbital properties of two stars characterized by high speed with respect to the Sun. We analyzed two high-resolution Subaru spectra employing the MyGIsFOS code, which allows to derive the detailed chemical abundances for 28 elements (C, N, O, Na, Mg, Al, Si, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Sr, Y, Zr, Ba, La, Ce, Pr, Nd, Sm, and Eu), and abundance from two ionization states in the case of four elements (Ti, Cr, Fe, and Zr). TYC 622–742–1 and TYC 1193–1918–1 are metal-poor stars ([Fe/H] of −2.37 and −1.60), they are similar in the chemical pattern with respect to Fe, they are urn:x-wiley:00046337:media:asna20210032:asna20210032-math-0001 enhanced and show a slight excess in Eu abundance. Both giant stars are poor in C and rich in N, as expected for evolved stars, and this fact is supported by the low urn:x-wiley:00046337:media:asna20210032:asna20210032-math-0002 isotopic ratio in TYC 1193–1918–1. Nevertheless, the C abundance of TYC 622–742–1 is particularly low. TYC 622–742–1 and TYC 1193–1918–1 have a similar chemical composition to the other Galactic halo stars of comparable metallicity. According to their kinematics, both stars belong to the Galactic halo, but they are not a part of the Gaia-Sausage-Enceladus structure.
DOI	10.1002/asna.20210032
外部リンクURL	https://ui.adsabs.harvard.edu/abs/2022AN....34310032M/abstract