What CoRoT tells us about δ Scuti stars

Existence of a regular pattern and seismic indices to characterize stars

¹ Observatoire de Paris, LESIA, UMR8109, Université Pierre et Marie Curie, Université Paris Diderot, PSL
² Institut d'Astrophysique et Geophysique, University of Liège, Belgium
³ Stellar Astrophysics Centre, Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, DK-8000 Aarhus C, Denmark
⁴ Instituut voor Sterrenkunde, KU Leuven, Celestijnenlaan 200B, 3001, Leuven, Belgium
⁵ Instituto de Astrofísica e Ciências do Espaço, Universidade do Porto, CAUP, Rua das Estrelas, PT4150-762 Porto Portugal
⁶ Dept. Física Teórica y del Cosmos. University of Granada, 18071, Granada, Spain
⁷ Instituto de Astrofísica de Canarias, 38200 La Laguna, Tenerife, Spain
⁸ Departamento de Astrofísica, Universidad de La Laguna, 38206 La Laguna, Tenerife, Spain

^* e-mail: Eric.Michelatobspm.fr

Published online: 27 October 2017

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 δ 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 δ Scuti stars, as Δv and v_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 ([1]) and Kepler ([2]). Finally, it sketches out the perspective of using δ Scuti stars pulsations for ensemble asteroseismology