2005PASJ...57...83T

begin{HTML} A method is presented for very accurately establishing the differences of the atmospheric parameters (the effective temperature, the surface gravity, the microturbulent velocity, and the Fe abundance) between two similar stars by using the equivalent widths of Fe <FONT SIZE="-2">I</FONT> and Fe <FONT SIZE="-2">II</FONT> lines, which is a variant of the numerical solution-search approach developed by Takeda et al. (2002, PASJ, 54, 451), while being inspired by the spirit of the orthodox ``differential curve-of-growth'' procedure. By applying this technique to eight selected stars similar to the Sun [HD 20630, 76151, 134987, 181655, 186408 (16 Cyg A), 186427 (16 Cyg B), 195019, and 217014] along with the Sun itself, the parameter differences between any pairs of these stars could be successfully determined to precisions of ∼ 10 K (in D<i>T</i><sub>eff</sub>), ∼ 0.02dex (in Dlog <i>g</i>), ∼0.02 km s<sup>-1</sup> (in D<i>v</i> <sub>t</sub>), and ∼ 0.01 dex (in D<i>A</i> <sub>Fe</sub>). Regarding 16 Cyg A and B, a well-known ``solar twin'' system where a planet has been detected only in B, the metallicities of these two components were concluded to be essentially the same to a level of \lesssim 0.01 dex.