Constraining the angular momentum of the Sun with planetary orbital motions and general relativity

The angular momentum of a star is an important astrophysical quantity related to its internal structure, formation and evolution. On average, helioseismology yields S = 1.92 10^41 kg m^2 s^-1 for the angular momentum of the Sun. We show how it should be possible to measure or, at least, constrain it in a near future by using the gravitomagnetic Lense-Thirring effect predicted by general relativity for the orbit of a test particle moving around a central rotating body. We also discuss the present-day situation in view of the latest determinations of the supplementary perihelion precession of Mercury.