Temporal Evolution of Main Sequence Dusty Disks

Abstract

Using the velocity dispersion as a statistical measure of age we constrain the ages of a large sample of Vega-like stars in order to study the temporal evolution of the dust disks around them. Fractional dust luminosity (f(d) = L-dust/L-{*}) of stars is taken as a measure of `dustiness' of the disks. The dustiness (f(d)) of the main sequence disks is found to decrease with increasing velocity dispersion. Since velocity dispersion of stars is known to increase with age as similar to t(1/3), a functional dependence of dustiness (f(d)) with age can be derived. fd is found to drop off with stellar age according to the power law f(d) proportional to (age)(-2.38). Ages of these main sequence dusty systems range from a few times 10(7) yr to a Gyr. The age distribution of Vega-like stars is found to be consistent with a constant rate formation of 10(-14) yr(-1) pc(-3) in the solar neighborhood.