Internal structure of KIC 9145955. The vertical red dashed lines in panels (a)–(d) denote the helium core boundary where the hydrogen mass fraction is about 0.01. The vertical orange dashed lines in panels (a)–(d) denote the base of the convection zone, which is marked as q_bcz. In panel (a), two horizontal dashed lines represent the range of observed frequencies. The purple dot indicates the Brunt–V﹩\ddot{{\rm{a}}}﹩is﹩\ddot{{\rm{a}}}﹩l﹩\ddot{{\rm{a}}}﹩ frequency N, and the blue dashed–dotted and light-blue dashed line indicate the characteristic acoustic frequencies S₁ and S₂, respectively. In panel (b), the continuous line and dotted line indicate the adiabatic and radiative temperature gradients. In panel (c), circles and the dotted line indicate the distribution of the hydrogen abundance and inner density. In panel (d), blue crosses represent the reaction rate of the carbon, nitrogen, and oxygen (CNO) cycle.