We present an analysis of the chemical abundances of the star Tycho G in the direction of the remnant of supernova ( SN ) 1572 , based on Keck high-resolution optical spectra .
The stellar parameters of this star are found to be those of a G-type subgiant with T _ { \mathrm { eff } } = 5900 \pm 100 K , \log ( g / { cm~ { } s } 2 ) = 3.85 \pm 0.30 dex , and \mathrm { [ Fe / H ] } = -0.05 \pm 0.09 .
This determination agrees with the stellar parameters derived for the star in a previous survey for the possible companion star of SN 1572 ( Ruiz-Lapuente et al .
2004 ) .
The chemical abundances follow the Galactic trends , except for Ni , which is overabundant relative to Fe , [ { Ni / Fe } ] = 0.16 \pm 0.04 .
Co is slightly overabundant ( at a low significance level ) .
These enhancements in Fe-peak elements could have originated from pollution by the supernova ejecta .
We find a surprisingly high Li abundance for a star that has evolved away from the main sequence .
We discuss these findings in the context of companion stars of supernovae .