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Title: 18 Sco: A solar twin rich in refractory and neutron-capture elements. Implications for chemical tagging

We study with unprecedented detail the chemical composition and stellar parameters of the solar twin 18 Sco in a strictly differential sense relative to the Sun. Our study is mainly based on high-resolution (R ∼ 110,000), high signal-to-noise ratio (800-1,000) Very Large Telescope UVES spectra, which allow us to achieve a precision of about 0.005 dex in differential abundances. The effective temperature and surface gravity of 18 Sco are T{sub eff} = 5823 ± 6 K and log g = 4.45 ± 0.02 dex, i.e., 18 Sco is 46 ± 6 K hotter than the Sun and log g is 0.01 ± 0.02 dex higher. Its metallicity is [Fe/H] = 0.054 ± 0.005 dex, and its microturbulence velocity is +0.02 ± 0.01 km s{sup –1} higher than solar. Our precise stellar parameters and differential isochrone analysis show that 18 Sco has a mass of 1.04 ± 0.02 M{sub ☉} and that it is ∼1.6 Gyr younger than the Sun. We use precise High Accuracy Radial velocity Planet Searcher (HARPS) radial velocities to search for planets, but none are detected. The chemical abundance pattern of 18 Sco displays a clear trend with condensation temperature, thus showing higher abundances of refractories inmore » 18 Sco than in the Sun. Intriguingly, there are enhancements in the neutron-capture elements relative to the Sun. Despite the small element-to-element abundance differences among nearby n-capture elements (∼0.02 dex), we successfully reproduce the r-process pattern in the Solar System. This is independent evidence for the universality of the r process. Our results have important implications for chemical tagging in our Galaxy and nucleosynthesis in general.« less
Authors:
; ; ;  [1] ;  [2] ; ; ;  [3] ; ;  [4] ;  [5] ; ;  [6] ;  [7] ;  [8]
  1. Departamento de Astronomia do IAG/USP, Universidade de São Paulo, Rua do Matão 1226, 05508-900 São Paulo, SP (Brazil)
  2. McDonald Observatory and Department of Astronomy, University of Texas at Austin (United States)
  3. Research School of Astronomy and Astrophysics, The Australian National University, Cotter Road, Weston, ACT 2611 (Australia)
  4. Department of Astronomy and Astrophysics, University of Chicago, 5640 South Ellis Avenue, Chicago, IL 60637 (United States)
  5. Institute of Astronomy, University of Cambridge, Madingley Road, CB3 0HA, Cambridge (United Kingdom)
  6. Departamento de Física Teórica e Experimental, Universidade Federal do Rio Grande do Norte, 59072-970 Natal, RN (Brazil)
  7. Centro de Astrofísica da Universidade do Porto, Rua das Estrelas, 4150-762 Porto (Portugal)
  8. Instituto de Fisica, Universidade Federal do Rio Grande do Sul, Av. Bento Goncalves 9500, Porto Alegre, RS (Brazil)
Publication Date:
OSTI Identifier:
22365422
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 791; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ACCURACY; CAPTURE; ELEMENT ABUNDANCE; GALAXIES; GRAVITATION; MASS; METALLICITY; NEUTRON REACTIONS; NUCLEOSYNTHESIS; PLANETS; R PROCESS; RADIAL VELOCITY; REFRACTORIES; RESOLUTION; SIGNAL-TO-NOISE RATIO; SOLAR SYSTEM; SUN; TELESCOPES; ULTRAVIOLET SPECTRA