Evolution of the Barium abundance in the early Galaxy from a NLTE analysis of the Ba lines in a homogeneous sample of EMP stars - Astrophysics > Astrophysics of GalaxiesReport as inadecuate




Evolution of the Barium abundance in the early Galaxy from a NLTE analysis of the Ba lines in a homogeneous sample of EMP stars - Astrophysics > Astrophysics of Galaxies - Download this document for free, or read online. Document in PDF available to download.

Abstract: Barium is a key element in constraining the evolution of the not wellunderstood r-process in the first galactic stars and currently the Baabundances in these very metal-poor stars were mostly measured under the LocalThermodynamical Equilibrium LTE assumption, which may lead in general to anunderestimation of Ba. We present here determinations of the barium abundancetaking into account the non-LTE NLTE effects in a sample of extremelymetal-poor stars EMP stars: 6 turnoff stars and 35 giants. The NLTE profilesof the three unblended Ba II lines 455.4, 585.3, 649.6nm have been computed.The computations were made with a modified version of the MULTI code, appliedto an atomic model of the Ba atom with 31 levels of Ba I, 101 levels of Ba II,and compared to the observations. The ratios of the NLTE abundances of bariumrelative to Fe are slightly shifted towards the solar ratio. In the plot ofBa-Fe versus Fe-H, the slope of the regression line is slightly reduced asis the scatter. In the interval -3.3


Author: S.M. Andrievsky GEPI, M. Spite GEPI, S. A. Korotin, F. Spite GEPI, P. Francois GEPI, P. Bonifacio GEPI, Cifist, R. Cayrel GEPI, V

Source: https://arxiv.org/







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