Particle motion in the vicinity of the protosun with variable luminosity

Variations of luminosity of the protosun during its Hayashi stage produced variations of its repulsive radiative action on small particles in its vicinity — or, in other words, variations of the effective mass of the protosun. Changes of the effective mass produced changes of size of orbits for particles circling around the protosun. When the luminosity increased, the effect of variable luminosity (EVL) diminished or overbalanced the Poynting-Robertson effect (PRE), hindering the small particles in their drift toward the protosun, and reinforced PRE when the luminosity decreased. An analysis of quasicircular motion of small uncharged particles moving in transparent circumsolar space under both effects — EVL and PRE — is given.