Local Stellar Kinematics from RAVE data - VI. Metallicity Gradients Based on the F-G Main-sequence Stars

TL;DR

This study analyzes metallicity gradients in F and G type dwarf stars from the RAVE DR4 database, revealing how metallicity varies with galactic radius and height, and highlighting differences between thin and thick disc stars.

Contribution

It provides detailed measurements of radial and vertical metallicity gradients for F and G dwarf stars, including their dependence on orbital parameters and vertical distance.

Findings

Radial metallicity gradients are negative within 500 pc but tend to be positive at larger heights.

Vertical metallicity gradients are approximately -0.176 and -0.119 dex/kpc for different vertical distance ranges.

Gradients vary with orbital elongation and galactocentric distance, indicating complex stellar population dynamics.

Abstract

We estimated iron and metallicity gradients in the radial and vertical directions with the F and G type dwarfs taken from the RAVE DR4 database. The sample defined by the constraints Zmax<=825 pc and ep<=0.10 consists of stars with metal abundances and space velocity components agreeable with the thin-disc stars. The radial iron and metallicity gradients estimated for the vertical distance intervals 0<Zmax<=500 and 500<Zmax<=800 pc are d[Fe/H]/dRm=-0.083(0.030) and d[Fe/H]/dRm=-0.048(0.037 )dex/kpc; and d[M/H]/dRm=-0.063(0.011) and d[M/H]/dRm=-0.028(0.057) dex/kpc, respectively, where Rm is the mean Galactocentric distance. The iron and metallicity gradients for less number of stars at further vertical distances, 800<Zmax<=1500 pc, are mostly positive. Compatible iron and metallicity gradients could be estimated with guiding radius (Rg) for the same vertical distance intervals 0<Zmax<=500 and 500<Zmax<=800 pc, i.e. d[Fe/H]/dRg=-0.083(0.030) and d[Fe/H]/dRg=-0.065(0.039) dex/kpc; d[M/H]/dRg=-0.062(0.018) and d[M/H]/dRg=-0.055(0.045) dex/kpc. F and G type dwarfs on elongated orbits show a complicated radial iron and metallicity gradient distribution in different vertical distance intervals. Significant radial iron and metallicity gradients could be derived neither for the sub-sample stars with Rm<=8 kpc, nor for the ones at larger distances, Rm>8 kpc. The range of the iron and metallicity abundance for the F and G type dwarfs on elongated orbits, [-0.13, -0.01), is similar to the thin-disc stars, while at least half of their space velocity components agree better with those of the thick-disc stars. The vertical iron gradients estimated for the F and G type dwarfs on circular orbits are d[Fe/H]/dZmax=-0.176(0.039) dex/kpc and d[Fe/H]/dZmax=-0.119(0.036) dex/kpc for the intervals Zmax<= 825 and Zmax<=1500 pc, respectively.