Effects of photophoresis on the evolution of transitional circumstellar disks

TL;DR

This study investigates how photophoresis influences the movement and distribution of solid particles in transitional circumstellar disks, revealing size-dependent migration patterns and potential belt formation effects.

Contribution

It is the first detailed analysis of photophoresis effects on disk evolution, considering multiple forces and applying to real and hypothetical systems.

Findings

Photophoresis causes size-dependent inward or outward migration of solids.

Photophoresis increases the stability distance of particles from the star.

Potential formation of belts of objects around low-luminosity stars due to photophoresis.

Abstract

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.