The Gas Drag Effect on the Elliptic Motion of a Solid Body in the Primordial Solar Nebula

The gas drag effect in the primordial solar nebula on the motion of a solid body, ranging from a large planetesimal to a small dust grain, is investigated. For a planetesimal, expressions for the short-term variation of the semi-major axis, the eccentricity and inclination are obtained using a perturbation method and a realistic formula for the gas drag force.