A possible method for detecting a convective core

Intermediate mass stars feature a convective core which is often confined in less than 10% of their radius. That implies a sound speed discontinuity at the core edge, which is seen in the eigenfrequencies. But, because of the very deep location, the classical use of the second difference fails to detect it. We propose here to look directly at the large separation, for the modes whose internal turning points are around the discontinuity. This method is first tested with the Sun to detect the discontinuity at the base of the convection zone, with degrees l = 20 to 50. Then it is applied to intermediate mass stars using low-degree modes l < 3 to explore the signature of a convective core. The example of α Centauri A is given. The evolution of the radiative core of young stars is also studied.SCOPUS: cp.p