Helioseismology and the solar age

Original · EN

The problem of measuring the solar age by means of helioseismology hasbeen recently revisited by Guenther & Demarque (1997) and by Weiss & Schlattl (1998). Different best values for t seis and different assessment of the uncertainty resulted from these two works. We show that depending on the way seismic data are used, one may obtain the value t seis≈ 4.6 Gy, close to the age of the oldest meteorites, t met=4.57 Gy, like in the first paper, or above 5 Gy like in the second paper. The discrepancy in the seismic estimates of the solar age may be eliminated by assuming higher than the standard metal abundance and/or an upward revision of the opacities in the solar radiative interior.We argue that the most accurate and robust seismic measure of the solar age are the small frequency separations, Dℓ,ₙ=νₗ,ₙ-νℓ₊₁,ₙ₋₁, for spherical harmonic degrees ℓ=0,2 and radial orders n≫ℓ.The seismic age inferred by minimization of the sum of squared differences between the model and the solar small separations is t seis=4.66±0.11, a number consistent with meteoritic data.Our analysis supports earlier suggestions of using small frequency separations as stellar age indicators.