On our Sun, the activity level is related to the chromospheric emission of the Ca II K line. The study of this activity is fundamental in the distinction between parasite signals and real ones and it enable us to detect the lowest-mass planets by radial velocity (RV) methods.

It is widely known that the presence of active regions, created by strong local magnetic phenomena, induces RV variations by different physical processes. In this context, we discuss the effects of active regions in the stellar activity and the possibility of modelling the chromospheric emission.

We present integrated changes in SOAP 2.0 software tool that incorporate simple models of chromospheric activity and we conclude about the importance of this study to push forward our ability to detect exoplanets.