Fundamental properties of low-mass stars in eclipsing binary systems

¹ LESIA-Observatoire de Paris, CNRS, UPMC Univ. Paris 06, Univ. Paris-Diderot, 5 place Jules Janssen, 92195 Meudon Cedex, France
² Institut d'Estudis Espacials de Catalunya (IEEC), C/ Gran Capità 2-4, 08028 Barcelona, Spain
³ Institut de Ciències de l'Espai (CSIC-IEEC), Campus UAB – Facultat de Ciències, Torre C5-parell 2 a planta, 08193 Bellaterra, Spain
⁴ Departament d'Astronomia i Meteorologia, Institut de Ciències del Cosmos (ICC), Universitat de Barcelona (IEEC-UB), C/ Martí i Franquès 1, 08028 Barcelona, Spain

Abstract

Eclipsing binary systems offer a unique opportunity to accurately measure the fundamental properties of stars. In the past years, masses and radii of low-mass stars in these systems have been obtained with uncertainties well below the 3% level, imposing stringent constrains on theoretical models. Several results revealed that there is a discrepancy between the radius predicted by models and that from the observations of about 5–10% depending on the mass range. On the other hand, effective temperatures are overestimated by models by about a 10%. These discrepancies have been usually attributed to stellar magnetic activity, however, the correct scenario is not yet clear. The progress in the understanding of stellar activity on low-mass stars and its relation with the radius discrepancies with models is summarized here both from the empirical and the theoretical points of view.