I. Study of data reduction and analysis of ACS/HST in UV line and continuum data for low-mass accreting T Tauri stars.II. Definition and implementation of a global software simulation package to assess and evaluate the performances of various detectors (CCD, CMOS,...) for high-precision measurements of various types of stars, applicable to both space and ground-based instrumentation. Application of this tool to the science detectors of the ESA M3 selected mission PLATO.status: publishe