Acoustic modes of 11 delta Scuti stars

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.