Spot modelling through multi-band photometry

Context. Stellar activity is comprised of various phenomena, mainly spots and faculae. It is one of the main sources of noise in exoplanetary observations because it affects both spectroscopic and photometric observations. In studying young active planetary systems, we need to model the activity of the host stars to remove astrophysical noise from our observational data. Aims. We model the contribution of stellar spots in photometric observations. Through the use of multi-band photometry, we aim to extract the geometric properties of the spots and constrain their temperatures. Methods. We analysed multi-band photometric observations acquired with the 80 cm Marcon telescope of the Osservatorio Polifunzionale del Chianti of V1298 Tau, assuming the photometric modulation observed in different bands is attributed to cold spots. Results We constrained the effective temperature of the active regions present on the surface of V1298 Tau, resulting from a combination of spots and faculae. We tested our hypothesis on solar data, verifying that we successfully measured the size of the dominant active region and its averaged effective temperature.