Stellar characterisation of FGKM dwarfs. Possible impact on the surface brightness color relation.

The study of stellar magnetic activity on different time scales is important because it provides insight into the physical mechanism behind the interaction between convection and the rotation of stars. On the one hand, the study of long-term activity through different spectral lines has been possible using spectroscopic data obtained from ground-based observations. On the other hand, satellite photometric observations (e.g. Kepler and TESS) permit us to deepen the field of short-term studies by obtaining stellar rotation periods and flare frequencies with higher precision. In addition, interferometric data allow us to study these objects in more detail and to characterise them by obtaining angular diameters, limb darkening, etc., which are essential parameters for the analysis of stellar and planetary characterisation. The combination of the three observational techniques mentioned above allows us to make progress in the understanding of the physical phenomena that govern the interior and exterior of stars, achieving a better understanding from the stellar dynamo to the planets that orbit around dwarf stars. In this work we present the study of some FGKM dwarf stars by spectroscopic and photometric observations as well as some preliminary results obtained through the interferometric technique using the Stellar Parameters and Images with a Cophased Array (SPICA) interferometer installed at the Center for High Angular Resolution Astronomy (CHARA) at the Mount Wilson Observatory.