The interstellar space is full of small corpuscles of various shapes, sizes and physicochemical properties. These cosmic drifters derive from a variety of sources. The accumulation of these particles in some particular regions of outer space is an important issue, since it may provide answers to various scientific questions, such as the formation of proto-nebulae, planetary rings, interstellar clouds etc. In this work we suggest a possible mechanism of the genesis of such phenomena by studying the distribution of equilibrium positions of small particles that travel in the neighborhood of a system consisting of three major bodies that are in syzygy. Two of these bodies have equal masses m and are located at equal distances from a third primary with a different mass m0=βm. We also consider that some or all these bodies are radiation sources with constant luminosity. Therefore, the particle is subjected not only to gravitational forces but to the radiation emitted from the primaries as well. For our investigation we adopt Radzievskii’s simplifying theory which is mainly based on Lebedev’s inverse square law. The particular problem is characterized by four parameters: the mass parameter , and the three radiation coefficients , and which express the ratio of the force due to radiation to the force due to gravitation. These coefficients depend both on the properties of the radiating body and on those of the individual particle. This means that for a given source with constant luminosity, the corresponding radiation coefficient b has a unique value that characterizes a particular particle. Since there are many particles that move in the neighborhood of the primaries and assuming that the gravitational force exceeds radiation, the b-coefficients may take any value between 0 and 1. In the gravitational case there are six equilibrium positions of the particle. Four of them are collinear, that is, they lie on the x-axis of syzygy of the primaries and the other two are triangular and lie on the perpendicular y-axis that passes through the center of mass of the system. When only the central body is a radiation source, the equilibrium positions are spread along the two coordinate axes forming a cross. In all the other cases, the triangular points are arranged in arcs centered either to the central primary or a peripheral one and the collinear points, particularly those that are close to the radiating primary, scatter on the x-axis on both sides of each primary. These distributions remain qualitatively the same when the mass parameter of the system changes. As a special case of our investigation we have studied the distribution of the equilibrium points in the photo-gravitational Copenhagen problem.