New values of gravitational moments J2 and J4 deduced from helioseismology

By applying the theory of slowly rotating stars to the Sun, the solar quadrupole and octopole moments J2 and J4 were computed using a solar model obtained from CESAM stellar evolution code (Morel (1997)) combined with a recent model of solar differential rotation deduced from helioseismology (Corbard et al. (2002)). This model takes into account a near-surface radial gradient of rotation which was inferred and quantified from MDI f-modes observations by Corbard and Thompson (2002). The effect of this observational near-surface gradient on the theoretical values of the surface parameters J2, J4 is investigated. The results show that the octopole moment J4 is much more sensitive than the quadrupole moment J2 to the subsurface radial gradient of rotation.