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18 Sco : a solar twin rich in refractory and neutron-capture elements, implications for chemical tagging

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18 Sco : a solar twin rich in refractory and neutron-capture elements, implications for chemical tagging

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Título 18 Sco : a solar twin rich in refractory and neutron-capture elements, implications for chemical tagging
Autor Meléndez, Jorge
Ramírez, Iván
Karakas, Amanda I.
Yong, David
Monroe, TalaWanda Rose
Bedell, Megan
Bergemann, Maria
Asplund, Martin
Maia, Marcelo Tucci
Bean, Jacob L.
Nascimento Júnior, José Dias do
Bazot, Michael
Brito, Alan Alves
Freitas, Fabrício Catani de
Castro, Matthieu Sébastien
Abstract 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 Teff = 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−1 higher than solar. Our precise stellar parameters and differential isochrone analysis show that 18 Sco has a mass of 1.04 ± 0.02M 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 in 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.
Contido em The astrophysical journal. Bristol. Vol. 791, no. 1 (Aug. 2014), 14, 14 p.
Assunto Captura radioativa de nêutrons
Composicao estelar
Condensação
Espectros estelares
Espectros ultravioleta
Movimento estelar
Nucleosíntese
Turbulencia
[en] Stars: abundances
[en] Stars: AGB and post-AGB
[en] Stars: fundamental parameters
[en] Sun: abundances
Origem Estrangeiro
Tipo Artigo de periódico
URI http://hdl.handle.net/10183/108037
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