Poynting-Robertson Effect and Small Eccentric Orbits

Perturbation equations of celestial mechanics in application to solar electromagnetic radiation are investigated. Special attention is payed to nearly circular orbis. Results of Klačka and Kaufmannová (1992) are generalized and various initial semi-major axes are taken into acount. Time-averaged (during one period) eccentricity decreases only during the first 25% of the total time of inspiralling toward the Sun. The value 25% hods for all initial values of semi-major axes (initialy circular orbits are supposed). The orbits become more and more eccentric in the subsequent orbital evolution.