The frequency separations of stellar p-modes

Aims. The purpose of this work is to investigate the characteristics of a new frequency separation of stellar p-modes. Methods. Frequency separations are deduced from the asymptotic formula of stellar p-modes. Then, using the theoretical adiabatic frequencies of stellar model, we compute the frequency separations. Results. A new separation σl−1l+1(n), which is similar to the scaled small separation dll+2(n)/(2l + 3), is obtained from the asymptotic formula of stellar p-modes. The separations σl−1l+1(n) and dll+2(n)/(2l + 3) have the same order. And like the small separation, σl−1l+1(n) is mainly sensitive to the conditions in the stellar core. However, with the decrease in the central hydrogen abundance of stars, the separations σ02 and σ13 deviate more and more from the scaled small separation. This characteristic could be used to extract the information on the central hydrogen abundance of stars.