Orbital Evolution of Particles Embedded in a Protoplanetary Disk and the Possibility of Observing Low-mass Planets in a Protoplanetary/Debris Disk

We investigate the motion of a particle in the vicinity of a low-mass planet embedded in a non-turbulent gaseous disk. We derive a general analytic formula that describes the change of the semi-major axis of the particle due to an encounter with the planet, using local approximation in a distant encounter regime. Our final formula includes the effects of steady, axisymmetric radial gas flow, the global gas pressure gradient in the disk, planet gravity, and the structure of the gas flow modified by the planet's gravity. We then discuss the conditions for a dust gap opening around a low mass planet and radial distribution of dust particles. We also discuss the possibility of observing a low-mass planet embedded in a protoplanetary disk or debris disk by future instruments such as ALMA or SKA.