We perform Molecular dynamics simulations on star polymers with different functionalities in solvents of various quality. The radial distribution of the monomers around the star center follows the predictions stemming from scaling theory. We demonstrate that not only the scaling but also the diffuse regime of the chains far from the center can be described by universal functions predicted from theory. Moreover, we measure the effective force between two such stars and show that it is purely repulsive for athermal solvents, with the repulsion being reduced for worsening solvent quality and an attraction appearing at intermediate star distances close to Theta-solvent conditions. A mean-field-type analytical approach is set forward to calculate the effective potential between star polymers not too close to the estimated Theta point.