The chemical compositions of solar twins in the open cluster M67

被引:67
作者
Liu, F. [1 ,2 ]
Asplund, M. [1 ]
Yong, D. [1 ]
Melendez, J. [3 ]
Ramirez, I. [4 ,5 ]
Karakas, A. I. [1 ,6 ]
Carlos, M. [3 ]
Marino, A. F. [1 ]
机构
[1] Australian Natl Univ, Res Sch Astron & Astrophys, Canberra, ACT 2611, Australia
[2] Lund Univ, Lund Observ, Dept Astron & Theoret Phys, Box 43, SE-22100 Lund, Sweden
[3] Univ Sao Paulo, Dept Astron IAG, Rua Matao 1226, BR-05508900 Sao Paulo, SP, Brazil
[4] Univ Texas Austin, Dept Astron, 2515 Speedway, Austin, TX 78712 USA
[5] Univ Texas Austin, McDonald Observ, 2515 Speedway, Austin, TX 78712 USA
[6] Monash Univ, Sch Phys & Astron, Monash Ctr Astrophys, Clayton, Vic 3800, Australia
基金
巴西圣保罗研究基金会; 澳大利亚研究理事会;
关键词
stars: abundances; stars: atmospheres; open clusters and associations: individual: NGC 2682 (M67); HIGH-PRECISION ABUNDANCES; METAL-POOR STAR; R-PROCESS; GIANT BRANCH; GALACTIC THIN; S-PROCESS; SIGNATURES; PLANETS; HOMOGENEITY; TRENDS;
D O I
10.1093/mnras/stw2045
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
Stars in open clusters are expected to share an identical abundance pattern. Establishing the level of chemical homogeneity in a given open cluster deserves further study as it is the basis of the concept of chemical tagging to unravel the history of the Milky Way. M67 is particularly interesting given its solar metallicity and age as well as being a dense cluster environment. We conducted a strictly line-by-line differential chemical abundance analysis of two solar twins in M67: M67-1194 and M67-1315. Stellar atmospheric parameters and elemental abundances were obtained with high precision using Keck/High Resolution Echelle Spectrometer spectra. M67-1194 is essentially identical to the Sun in terms of its stellar parameters. M67-1315 is warmer than M67-1194 by a parts per thousand 150 K as well as slightly more metal-poor than M67-1194 by a parts per thousand 0.05 dex. M67-1194 is also found to have identical chemical composition to the Sun, confirming its solar-twin nature. The abundance ratios [X/Fe] of M67-1315 are similar to the solar abundances for elements with atomic number Z a parts per thousand currency sign 30, while most neutron-capture elements are enriched by a parts per thousand 0.05 dex, which might be attributed to enrichment from a mixture of asymptotic giant branch ejecta and r-process material. The distinct chemical abundances for the neutron-capture elements in M67-1315 and the lower metallicity of this star compared to M67-1194, indicate that the stars in M67 are likely not chemically homogeneous. This poses a challenge for the concept of chemical tagging since it is based on the assumption of stars forming in the same star-forming aggregate.
引用
收藏
页码:696 / 704
页数:9
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