出版社：SISSA, Scuola Internazionale Superiore di Studi Avanzati
摘要：We present a detailed abundance analysis of the strongly r−process enhanced giant star newly discovered in the HERES project, HE 2327-5642, for which [Fe/H] = −2.78 and [r/Fe] = +0.99. The determination of the stellar parameters and element abundances was based on analysis of high-quality VLT/UVES spectra. The surface gravity was calculated from the non-local thermodynamic equilibrium (NLTE) ionization balance between Fe I and Fe II, and Ca I and Ca II. Accurate abundances were determined for a total of 40 elements and for 23 neutron-capture elements beyond Sr and up to Th. The heavy element abundance pattern of HE 2327-5642 is in excellent agreement with those previously derived for other strongly r−process enhanced stars. Elements in the range from Ba to Hf match the scaled Solar r−process pattern very well. No firm conclusion can be drawn with respect to a relationship between the first n-capture peak elements, Sr to Pd, in HE 2327-5642 and the Solar r−process, due to the uncertainty of the latter. A clear distinction in Sr/Eu abundance ratios was found between the halo stars with different europium enhancement. HE 2327-5642 is suspected to be radial-velocity variable based on our high-resolution spectra, covering ∼ 4.3 years.
