  Although known for almost a century, the photophoretic force has only
recently been considered in astrophysical context for the first time. In our
work, we have examined the effect of photophoresis, acting together with
stellar gravity, radiation pressure, and gas drag, on the evolution of solids
in transitional circumstellar disks. We have applied our calculations to four
different systems: the disks of HR 4796A and HD 141569A, which are several Myr
old AB-type stars, and two hypothetical systems that correspond to the solar
nebula after disk dispersal has progressed sufficiently for the disk to become
optically thin. Our results suggest that solid objects migrate inward or
outward, until they reach a certain size-dependent stability distance from the
star. The larger the bodies, the closer to the star they tend to accumulate.
Photophoresis increases the stability radii, moving objects to larger
distances. What is more, photophoresis may cause formation of a belt of
objects, but only in a certain range of sizes and only around low-luminosity
stars. The effects of photophoresis are noticeable in the size range from
several micrometers to several centimeters (for older transitional disks) or
even several meters (for younger, more gaseous, ones). We argue that due to gas
damping, rotation does not substantially inhibit photophoresis.
