Effects of errors in the solar radius on helioseismic inferences

Frequencies of intermediate-degree f-modes of the Sun seem to indicate that the solar radius is smaller than what is normally used in constructing solar models. We investigate the possible consequences of an error in radius on results for solar structure obtained using helioseismic inversions. It is shown that solar sound speed will be overestimated if oscillation frequencies are inverted using reference models with a larger radius. Using solar models with radius of 695.78 Mm and new data sets, the base of the solar convection zone is estimated to be at radial distance of 0.7135 ± 0.0005 of the solar radius. The helium abundance in the convection zone as determined using models with OPAL equation of state is 0.248±0.001, where the errors reflect the estimated systematic errors in the calculation, the statistical errors being much smaller. Assuming that the OPAL opacities used in the construction of the solar models are correct, the surface Z/X is estimated to be 0.0245± 0.0006.