The stellar metallicity distribution in intermediate latitude fields with BATC and SDSS data

TL;DR

This study uses BATC and SDSS photometric data to analyze the metallicity distribution of approximately 40,000 main-sequence stars across different Galactic regions, revealing gradients and variations with distance and height.

Contribution

It presents a large-scale photometric metallicity analysis of main-sequence stars in the Galaxy using SED fitting, providing new insights into metallicity gradients and distribution patterns.

Findings

Metallicity shifts from metal-rich to metal-poor with increasing distance from Galactic center.

Mean metallicity is about 1.5 dex in the outer halo and 1.3 dex in the inner halo.

Vertical metallicity gradients vary across Galactic components, with significant gradients in the thin and thick disks, but little in the halo.

Abstract

Based on the Beijing-Arizona-Taiwan-Connecticut (BATC) and Sloan Digital Sky Survey (SDSS) photometric data, we adopt SEDs fitting Method to evaluate the metallicity distribution for \sim40,000 main-sequence stars in the Galaxy. According to the derived photometric metallicities of these sample stars, we find that the metallicity distribution shift from metal-rich to metal-poor with the increase of distance from the Galactic center. The mean metallicity is about of 1.5 \pm 0.2dex in the outer halo and 1.3 \pm 0.1 dex in the inner halo. The mean metallicity smoothly decreases from -0.4 to -0.8 in interval 0 < r \leq 5 kpc. The fluctuation in the mean metallicity with Galactic longitude can be found in interval 4 < r \leq 8 kpc. There is a vertical abundance gradients d[Fe/H]/dz\sim -0.21 \pm 0.05 dex kpc-1 for the thin disk (z \leq 2 kpc). At distance 2 < z \leq 5 kpc, where the thick disk stars are dominated, the gradients are about of -0.16 \pm0.06 dex kpc-1, it can be interpreted as a mixture of stellar population with different mean metallicities at all z levels. The vertical metallicity gradient is - 0.05 \pm0.04 dex kpc-1 for the halo (z > 5 kpc). So there is little or no metallicity gradient in the halo.