New seismic diagnostic techniques were developed for measuring stellar properties with high accuracy, such as the depth of the surface convection zone, stellar age and chemical abundance, of the Sun and of stars similar to the Sun. One of the main results of this research work is that, with the help of our newly developed seismic diagnostic technique, the determined seismic solar age is 4.60 ± 0.04 billion years, which is similar to, although somewhat greater than, today’s commonly adopted values. We also determined seismically the solar surface heavy-element abundance by mass, 0.0142 ± 0.0005, which is substantially smaller than the value used in standard solar modelling, but it is similar to, though by about 6% larger than, the value reported by other research groups using numerical simulations of the solar atmosphere. The results of this study are of great importance to other fields in astronomy, such as the chemical evolution of the Galaxy, and hence of the Universe. The consequences are bound to elevate to new heights the sophistication of the theory of the evolution of stars, the backbone of theoretical astrophysics.

Furthermore, a model for stellar convection was generalized to a nonzero background flow, with the principal motivation of studying nonradial oscillations of stars with turbulent convection zones. The most important outcome of our extended convection model is that the nonzero background flow reduces the magnitude of the heat flux, generating a component perpendicular to the temperature gradient in the direction of the flow; it also modifies the diagonal components of the Reynolds stress, and generates off-diagonal components. This result is of immediate importance to stellar pulsation mode physics. The reduction of the heat flux in a background shearing flow will affect, for example, the oscillation amplitudes in solar-type stars, which are now measured with high accuracy using NASA’s Kepler satellite.

The outcome of this project also helps to determine with higher accuracy some of the key properties of planets around stars outside our solar system, now detected with NASA’s exo-planet mission Kepler, such as the planetary radii, and whether or not the planets are capable of sustaining life.