VARIATION OF THE RADIAL AND VERTICAL METALLICITY GRADIENTS IN THE GALACTIC DISK WITH AGE

Based on a previously compiled catalog of fundamental astrophysical parameters for nearby disk F stars (containing, in particular, metallicities, isochronal ages, and space-velocity components), which were derived from published astrometric and photometric data, the Galactic orbital elements were calculated for 1630 stars. The eccentricity e, apogalactic orbital radius R(a), and maximum height Z(max) of a star above the Galactic plane are shown to correlate with age, and, therefore, may serve as its statistical indicators. The radial and vertical metallicity gradients were found for mixed-age stars and for a few narrow age ranges. The radial gradient for mixed-age stars was estimated from apogalactic distances and-from mean orbital radii [R] to be d[Fe/H]/dR(a) = (-0.045 +/- 0.005) kpc(-1) and d[Fe/H]/d[R] = (-0.09 +/- 0.01) kpc(-1), respectively. The vertical gradient for the same stars is d[Fe/H]/dZ(max) = (-0.33 +/- 0.04) kpc(-1). It was established that the values of all the gradients systematically decreased when passing to older stars. It is shown that after allowing for the radial gradient, the vertical gradient, while decreasing by approximately a quarter, preserves the pattern of its variation with age.