Element Abundances Of The Sun Nearest Neighbor Dwarf

The abundances of elements in stars is an important probe to study the chemical evolution of the Galaxy. Analysis about the abundance in different stellar populations is a very important subject in study of the structure and chemical evolution of the Galaxy.Our work includes two parts: first, we selected a sample of stars from the latest catalogue of the star survey in the solar neighbourhood, the high resolution and high signal-to-noise ratio spectra of 26 F- and G- dwarfs were obtained with the CoudéEchelle Spectrograph mounted on the 2.16 m telescope at the National Astronomical Observatories (Xinglong, China). The spectra were reduced and equivalent widths of each spectra line were measured with MIDAS routines. The abundances of 14 elements (O, Na, Mg, Al, Si, Ca, Fe, Sc, Ti, V, Cr, Mn, Ni and Ba) in these sample stars were calculated based on the model atmospheres and atomic line data; secondly, we compiled a sample of 540 stars from 11 literatures with the data of abundances, then the population membership of each star was determined using an uniform standard of kinematics, 270 belong to the thin disk, 170 stars belong to the thick disk, and 100 belong to the halo. Finaly,the abundance trends of 22 elements ( Na, Mg, Al, Si, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Sr, Zr Y, Ba, Ce, Nd and Eu ) in different stellar populations were discussed.Our main conclusions are as following:(1) The thick disk and the thin disk stars are blended in metallicity, so for the thick and halo stars. But on the average, the metallicities of thin disk stars are mostly in the range -0.7≤[Fe/H]≤0.4, for the thick disks -1.0≤[Fe/H]≤-0.3, and for most halo stars [Fe/H]≤-0.7.(2) In the metallicity range -0.7≤[Fe/H]≤-0.3, where the overlap range for thin and thick stars, the abundance ratio [a/Fe] in thick disk stars show a clear enhancement compared to thin disk stars. Some other elements, such as Al, Sc, V, Co, Cu Zn and Eu, the abundance also show a clear separation between the thin and thick disk satrs. However, the abundances of Na, Cr, Ni, Ba, Y, and Ce do not show cleaer separations between the thin and thick disk satrs.(3) For halo and thick disk stars, the abundances of each element are heavy blended in the whole range of metallicity.