**full Title** Asp Conference Series, Vol. **volume**, **year of Publication** **names of Editors** Testing Low-mass Stellar Models: Three New Detached Eclipsing Binaries below 0.75m ⊙

Full tests to stellar models below 1M⊙ have been hindered until now by the scarce number of precise measurements of the stars’ most fundamental parameters: their masses and radii. With the current observational techniques, the required precision to distinguish between different models (errors < 2-3 %) can only be achieved using detached eclipsing binaries where 1) both stars are similar in mass, i.e. q = M1/M2 ∼ 1.0, and 2) each star is a main sequence object below 1M⊙. Until 2003 only three such binaries had been found and analyzed in detail. Two new systems were published in 2005 (Creevey et al.; López-Morales & Ribas), almost doubling the previous number of data points. Here we present preliminary results for 3 new low-mass detached eclipsing binaries. These are the first studied systems from our sample of 41 new binaries (Shaw & LópezMorales, this proceedings). We also provide an updated comparison between the Mass–Radius and the Mass–Teff relations predicted by the models and the observational data from detached eclipsing binaries. We define low-mass stars as main sequence stars with masses between 1M⊙ and the Hydrogen burning limit (0.07–0.08M⊙). Low-mass stars are small cool objects, with radii between 1.0 and 0.1R⊙ and effective surface temperatures between 6000 and 2500 K. They are also faint as their luminosities between 1 and 10−4L⊙ reveal. They are the most abundant stars in the Galaxy, where least 7 of every 10 stars are low-mass main sequence stars. These objects play a role on studies of baryonic dark matter (it is thought that low-mass stars, brown dwarfs, and stellar remnants are the main contributors to the baryonic dark matter in the Universe), on dynamical studies of galaxies and star clusters, and on the detailed characterization of the stars in the solar neighborhood, where intensive searches for Earth-like planets around low-mass stars are currently underway. Low-mass stars are also a subject of interest in other fields in physics, given the complicated physical processes that are taking place in these stars. H2 molecules, TiO, H2O, CO, and CN become stable in the atmosphere of low-mass stars at temperatures below 5000–4000 K. Below 2800 K, even more complex molecular compounds, such as CaTiO3, Al2O3, and Mg2SiO4, also become stable. Therefore any model trying to reproduce how the radiation is transmitted from the interior of the stars through their atmospheres needs to take into account the effect of all these molecules and compounds. The interior physics of