18 Sco: A SOLAR TWIN RICH IN REFRACTORY AND NEUTRON-CAPTURE ELEMENTS. IMPLICATIONS FOR CHEMICAL TAGGING*

摘要: We study with unprecedented detail the chemical composition and stellar parameters of solar twin 18 Sco in a strictly differential sense relative to Sun. Our 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 achieve precision about 0.005 dex abundances. The effective temperature surface gravity are T{sub eff} = 5823 ± 6 K log g 4.45 0.02 dex, i.e., 46 hotter than Sun 0.01 higher. Its metallicity [Fe/H] 0.054 its microturbulence velocity +0.02 km s{sup –1} higher solar. precise isochrone analysis show that has mass 1.04 M{sub ☉} it ∼1.6 Gyr younger use High Accuracy Radial Planet Searcher (HARPS) radial velocities search for planets, but none detected. abundance pattern displays clear trend condensation temperature, thus showing abundances refractories more » Intriguingly, there enhancements neutron-capture elements Despite small element-to-element differences among nearby n-capture (∼0.02 dex), we successfully reproduce r-process Solar System. This independent evidence universality r process. results have important implications tagging our Galaxy nucleosynthesis general. « less