Pressure gradient parameter η as a functionof orbital distance from the planet for α = 0.001, H∕r = 0.05, and differentplanetary masses. The location of the planet is fixed at r = 1. A negative η parameter indicates the formation of a pressure bump and with it super-Keplerian gas velocities that stop the inwards drift of pebbles. Here a mass of about 25 Earth masses is needed to generate the pressure bump outside of the planetary orbit. Inside of the planetary orbit, η is always positive.