2020MNRAS.497.4042Z

The ratio of small-to-large separations r₀₁₀ has been widely used in helioseismology and asteroseismology to investigate the internal structure of a star, as it is approximately independent of the structure of the outer layers. Several studies have used this tool to constrain the convective-core overshooting of main-sequence stars (i.e. 0.0 <= δ_ov <= 0.2). This is consistent with the generally accepted values. However, Yang et al. have proposed that there is large convective-core overshooting in the Kepler targets KIC 2837475 and 11081729: 1.2 <= δ_ov <= 1.6 and 1.7 <= δ_ov <= 1.8, respectively. These are much larger than the normal values. Thus, the aim of this study is to re-investigate the ratios of the two stars using a model-independent method with the latest p-mode observations. Our results indicate that there is no robustness for including such a large convective-core overshooting while modelling these two stars. In fact, this leads to over-fitting, and the observational constraints of r₀₁₀ prefer models with a normal convective-core overshooting (i.e. 0.0 <= δ_ov <= 0.2) as the candidates for the best-fitting model of KIC 2837475 and 11081729.