SIMBAD references

The small separation (δν₀₁, δν₀₂ and δν₁₃) between oscillations with low degree l is dependent primarily on the sound speed profile within the stellar core, where nuclear evolution occurs. The detection of such oscillations in a star offers a very good opportunity to determine the stage of its nuclear evolution, and hence its age. In this context, we investigate the Sun and α Cen A and B. For α Cen A and B, each of the small separations δν₀₁,δν₀₂ and δν₁₃ gives a different age. Therefore, in our fitting process, we also employ the second difference, defined as ν_n,2_- 2ν_n,1_+ ν_n,0_, which is 2δν₀₁- δν₀₂. In addition to this, we use the frequency ratio (ν_n,0_/νn,2_). For the Sun, these expressions are equivalent and give an age of about 4.9-5.0 Gyr. For α Cen A and B, however, the small separation and the second difference give very different ages. This conflict may be resolved by the detection of oscillation frequencies that can be measured much more precisely than the current frequencies. When we fit the models to the observations, we find that (i) Z₀= 0.020,t = 3.50 Gyr and M_B= 1.006M_☉ from the small separations δν₀₁, δν₀₂ and δν₁₃ of α Cen B; and (ii) a variety of solutions from the non-seismic constraints and δν₀₂ of α Cen A and B, in which the masses of α Cen A and B are slightly modified and the age of the system is about 5.2-5.3 Gyr. For Z = 0.025, the closest masses we find to the observed masses are M_B= 0.922M_☉ and M_A= 1.115M_☉. The differences between these masses and the corresponding observed masses are about 0.01M_☉.