Based on synthetic flux spectra calculated from theoretical atmospheric models , a calibration of temperature and metallicity for the dwarfs observed in the Beijing-Arizona-Taiwan-Connecticut ( BATC ) multicolor photometric system is presented in this paper .
According to this calibration , stellar effective temperatures can be obtained from some temperature–sensitive color indices .
The sample stars have colors and magnitudes in the ranges 0.1 < d - i < 0.9 and 14.0 < i < 20.5 .
The photometric metallicities for these sample stars can be derived by fitting SEDs .
We determine the average stellar metallicity as a function of distance from the Galactic plane .
The metallicity gradient is found to be d [ Fe/H ] /d z = -0.37 \pm 0.1 dex/kpc for z < 4 kpc and d [ Fe/H ] /d z = -0.06 \pm 0.09 dex/kpc between 5 and 15 kpc .
These results can be explained in terms of different contributions in density distribution for Galactic models ‘ thin disk ’ , ‘ thick disk ’ and ‘ halo ’ components .
However , for the gradient in z > 5 kpc , it could not be interpreted according to the different contributions from the three components because of the large uncertainty .
So it is possible that there is little or no gradient for z > 5 kpc .
The overall distribution shows a metallicity gradient d [ Fe/H ] /d z = -0.17 \pm 0.04 dex/kpc for z < 15 kpc .