Chemical Evolution of Zinc in the Galaxy

The local thermodynamic equilibrium (LTE) abundances of zinc (Zn) of our sample of 35 metal-poor stars were explored in the range of -3.0 < [Fe/H] < 0.0. Based on a combination of our Zn abundances and those obtained in the literature, the behavior of Zn was investigated in the range of -4.2 < [Fe/H] < +0.5. The main results are as follows: (1) No clear separation in [Zn/Fe] behavior was found between halo, thick disk, and thin disk stars in our sample. (2) The decreasing trend of [Zn/Fe] with the increase of [Fe/H] was found to be confirmed to -4.2 < [Fe/H] <= -2.0, and to be explained by a chemical evolution model constructed with models of core-collapse supernovae (SNe) II or hypernovae (HNe) of Population III stars. (3) In -2.0 < [Fe/H] < +0.5, [Zn/Fe] follows a nearly flat trend with a slight enhancement of similar to +0.07dex up to [Fe/H] = -1.0, and shows the more enhanced trend in -1.0 < [Fe/H] <= -0.5, and then gradually decreases to an almost solar value in [Fe/H] > -0.5. This trend is better explained by a chemical evolution model constructed with models of normal SNe II, HNe, and SNe la, in which the metallicity effect and the single-degenerate scenario of the SNe la model are incorporated.