Revealing the population of the young ASCC 20

We present the study of the open cluster ASCC-20. This young stellar association located at 450 pc and A_V = 0.129 mag is ˜ 20 Myr old based on the upper main sequence fitting. We have created a multi-wavelength photometric catalogue of cluster candidate members by using archival data and data-mining techniques. The complete set of photometric bands contains: B_TV_T from Tycho-2, griz from SDSS, JHK_s from 2MASS and W1W2W3W4 from WISE. In addition, we have followed-up 36 of our photometric candidates by using spectroscopic data with CAHA-TWIN. We have derived spectral types and confirmed their membership: 1) 50% of these sources are M dwarfs with the Hα spectral feature in emission; 2) models (Allard et al., 2012) indicate a mass of ˜0.25 M_{⊙} for the faintest object confirmed by spectroscopy, a M7. We have re-observed a subsample of 11 confirmed members of M spectral type and measured features related with their youth (e.g.: Li at 6707.8 A) and metallicities by using GTC-OSIRIS at mid-resolution. Assuming a distance of 450 pc we report a Lithium Depletion Boundary age above 30 Myr, based on the faintest member of our sample without lithium (a M7). However a new study of the distance with Gaia will release a new insigth in the age of this cluster.