What CoRoT tells us about {\delta} Scuti stars existence of a regular pattern and seismic indices to characterize stars

Abstract

Inspired by the so appealing example of red giants, where going from a handful of stars to thousands revealed the structure of the eigenspectrum, we inspected a large homogeneous set of around 1860 {\delta} Scuti stars observed with CoRoT. This unique data set reveals a common regular pattern which appears to be in agreement with island modes featured by theoretical non-perturbative treatments of fast rotation. The comparison of these data with models and linear stability calculations suggests that spectra can be fruitfully characterized to first order by a few parameters which might play the role of seismic indices for {\delta} Scuti stars, as {\Delta \nu} and {\nu_{max}} do for red giants. The existence of this pattern offers an observational support for guiding further theoretical works on fast rotation. It also provides a framework for further investigation of the observational material collected by CoRoT and Kepler. Finally, it sketches out the perspective of using {\delta} Scuti stars pulsations for ensemble asteroseismology.