Interferometric survey of stellar parameters. Towards homogeneous FGK stars parameters and surface-brightness color relation in the context of PLATO space mission
Estimations of stellar angular diameters can be determined based on the surface brightness-colour relation (SBCR) and photometry. In the context of the PLATO space mission, the SBCR is considered to be an independent empirical alternative for estimating the stellar radii of FGK stars. We implemented a homogeneous approach, not only for calibrating the SBCR for FGK-IV/V stars, but also for determining their fundamental parameters. This made it possible to reliably place the stars on the Hertzsprung-Russell (HR) diagram and to study their impact on the SBC relations. We performed interferometric observations of 18 quiescent FGK-IV/V stars in the Gaia magnitude range of . For the first time, we used three different interferometric instruments operating in the , , and bands to measure the polychromatic limb-darkened angular diameters. In parallel, by using public domain spectra, we were able to estimate the stellar parameters (T_ . 3.088 łeq G łeq 5.498 R H K łog g, and Z) by using the open Python tool iSpec We achieved an average accuracy of 2.3% for the limb-darkened angular diameters based on polychromatic observations. However, we observed that our SBCR relation does not follow the calibration of the SBC relations in Gaia found in the literature. Furthermore, we found that the łog g and Z parameters have no impact on this relationship. Given the characteristics of our sample of quiescent stars, it constitutes an ideal set of targets for conducting a new SBCR calibration within the framework of the PLATO space mission. In this context, we report a SBCR calibration with σ_ RMS = 0.012, 0.009, and 0.009 in the G, G_ BP , and G_RP Gaia bands, respectively. This work is part of a series of papers reporting the first results obtained using a polychromatic approach to measure angular diameters, employing a fully homogeneous methodology for determining the fundamental parameters of stars and measuring the limb-darkened angular diameters