The stellar metallicity distribution of the Milky Way from the BATC survey

TL;DR

This study calibrates stellar metallicity and temperature using SDSS spectra and BATC photometry, revealing metallicity distribution peaks at different Galactic components and their invariance with distance from the plane.

Contribution

Developed a polynomial calibration method for BATC photometry to evaluate stellar parameters, enabling large-scale metallicity mapping of the Milky Way.

Findings

Metallicity peaks at [Fe/H] ~ -1.5 for halo stars

Metallicity peaks at [Fe/H] ~ -0.7 for thick disk stars

Metallicity distribution remains invariant with distance from the Galactic plane

Abstract

Using the stellar atmospheric parameters such as effective temperature and metallicity derived from SDSS spectra for 2200 main sequence (MS) stars which were also observed by Beijing - Arizona - Taiwan - Connecticut (BATC) photometric system, we develop the polynomial photometric calibration method to evaluate the stellar effective temperature and metallicity for BATC multi-color photometric data. This calibration method has been applied to about 160 000 MS stars from 67 BATC observed fields. Those stars have colors and magnitudes in the ranges 0.1 < d - h < 1.4 and 14.0 < d < 21.0. We find that there is a peak of metallicity distribution at [Fe/H] ~ -1.5 in the distance from the Galactic plane |Z| > 5 kpc which corresponds to the halo component and a peak at [Fe/H] ~ -0.7 in the region 2 < |Z| < 5 kpc where is dominated by the thick disk stars. The mean stellar metallicity smoothly decreases from -0.65 to -0.78 in the interval 0.5 < |Z|< 2 kpc. Metallicity distributions in the halo and the thick disk seem invariant with the distance from the Galactic plane.