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

We estimated iron and metallicity gradients in the radial and vertical directions with the F and G type dwarfs taken from the Radial Velocity Experiment Data Release 4 database. The sample defined by the constraints Z(max) <= 825 pc and e(p) <= 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 < Z(max) <= 500 and 500 < Z(max) <= 800 pc are d[Fe/H]/dR(m) = -0.083 +/- 0.030 and d[Fe/H]/dR(m) = -0.048 +/- 0.037 dexkpc(-1), and d[M/H]/dR(m) = -0.063 +/- 0.011 and d[M/H]/dR(m) = -0.028 +/- 0.057 dex kpc(-1), respectively, where Rm is the mean Galactocentric distance. The iron and metallicity gradients for less number of stars at further vertical distances, 800 < Z(max) <= 1500 pc, are mostly positive. Compatible iron and metallicity gradients could be estimated with guiding radius (Rg) for the same vertical distance intervals 0 < Z(max) <= 500 and 500 < Z(max) <= 800 pc, i.e. d[Fe/H]/dR(g) = -0.083 +/- 0.030 and d[Fe/H]/dR(g) = -0.065 +/- 0.039 dex kpc(-1); d[M/H]/dR(g) = -0.062 +/- 0.018 and d[M/H]/dR(g) = -0.055 +/- 0.045 dex kpc(-1). 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 R-m <= 8 kpc, nor for the ones at larger distances, R-m > 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]/dZ(max) = -0.176 +/- 0.039 dex kpc(-1) and d[Fe/H]/dZ(max) = -0.119 +/- 0.036 dex kpc(-1) for the intervals Z(max) <= 825 and Z(max) <= 1500 pc, respectively.