2018ApJ...855...16Z

We have analyzed 18 quarters of long-cadence data of KIC 9145955 provided by Kepler, and extracted 61 oscillation frequencies from these high-precision photometric data. The oscillation frequencies include 7 l = 0 modes, 44 l = 1 modes, 7 l = 2 modes, and 3 l = 3 modes. We identify l = 0 modes as p modes and l = 2 modes as p-dominated modes. For l = 1 modes, all of them are identified as mixed modes. These mixed modes can be used to determine the size of the helium core. We conduct a series of asteroseismic models and the size of the helium core is determined to be M_He = 0.210 ± 0.002 M_☉ and R_He=0.0307±0.0002R_☉. Furthermore, we find that only the acoustic radius τ₀ can be precisely determined with the asteroseismic method independently. The value of τ₀ is determined to be 0.494 ± 0.001 days. By combining asteroseismic results and spectroscopic observations, we obtain the best-fitting model. The physical parameters of this model are M = 1.24 M_☉, Z = 0.009, α = 2.0, T_eff = 5069 K, log g = 3.029, R = 5.636 R_☉, and L = 18.759 L_☉. In addition, we think that the observed frequency F39 (96.397 µHz) is more appropriate to be identified as a mixed mode of the most p-dominated.