Meridional section of an axisymmetric linear force-free field with an azimuthal flux rope encircling the star. The green solid lines are the field lines of the stellar coronal field, the orange dot is a close-in planet from which matter can evaporate and, after moving towards the star along the field lines, condense in the potential well to form a prominence-like structure (in red). The red dashed line on the equatorial plane of the star marks the locus of the minimum gravitational potential along field lines where condensations can be stably stored. The unit of measure is the radius R_∗ of the star, with the z axis being the axis of symmetry of the field and x the distance from the z axis.