The main goal of this work is to date young open clusters using delta Sct stars. Seismic indices as the large separation and the frequency at maximum power can help to constrain the models in order to better characterize the stars. We propose a reliable method to identify some radial modes, which gives us greater confidence in the constrained models. We extract the frequency content of a sample of delta Sct stars belonging to the same open cluster. We estimate the low-order large separation by means of different techniques and the frequency at maximum power for each member of the sample. We use a grid of models built with the typical parameters of delta Sct stars, including mass, metallicity and rotation as independent variables, in order to determine the oscillation modes. We select the observed frequencies whose ratios match those of the models. Once we find a range of radial modes matching the observed frequencies, mainly the fundamental mode, we add it to the other seismic parameters to better constrain the stellar age. Assuming star groups have similar chemistry and age, we estimate their mean age by computing a Weighted Probability Density Function fit to the age distribution of the seismically constrained models. We estimate the age of Trumpler 10 to be 30_-20_^+30^Myr, and Praesepe, to be 580+/-230Myr. In this latter case, we find two apparent populations of delta Sct stars in the same cluster, one at 510+/-140Myr and another at 890+/-140Myr. This may be due to two different formation events, the different rotational velocities of the members in our sample of stars, as a rapid rotation may modify the observed large separation, or to be members of unresolved binary systems.

Cone search capability for table J/A+A/675/A167/stars (List of studied delta Scuti)