Author(s): , , ,
Institution(s): 1. Konkoly Observatory, 2. Los Alamos National Laboratory
Asteroseismology allows unique information on the inner structure of stars. The large separation between the consecutive radial orders and the small separation of the modes with different l values are well-known and useful parameters characterizing solar-type oscillations. The large separation was derived only for a few Delta Scuti stars which are pulsating in the non-asymptotic regime. Theoretical investigations do not predict a high level of regularity of the excited modes. We carried out a search for regularity in a sample of Delta Scuti stars observed by CoRoT (91 stars). Usually the Fourier Transform or the histogram of frequency differences were used. The echelle diagrams represent the regularity when it was found. As a preliminary step we isolated set(s) of frequencies with quasi-equal spacing. Surprisingly not only a single pattern but up to six patterns were found in most of the stars. The patterns are regularly shifted with respect to each other. The echelle diagrams helped to reduce the scatter of the spacing. The derived spacing supported the better interpretation of the FT diagrams. There is no doubt of the existence of regular patterns. The interpretation is questionable: do the Delta Scuti stars behave so regularly, or we are faced with a technical pattern that obscures the real frequency pattern of the low amplitude Delta Scuti pulsation?